0000051644-21-000012 | 10-K | XBRL Viewer | Interpublic Group OF Companies INC

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Document and Entity Information Document - USD ($)	12 Months Ended
Document and Entity Information Document - USD ($)	Dec. 31, 2020	Feb. 11, 2021	Jun. 30, 2020
DEI [Abstract]
Document Annual Report	true
Document Information [Line Items]
Document Type	10-K
Document Period End Date	Dec. 31, 2020
Document Transition Report	false
Entity File Number	1-6686
Entity Registrant Name	INTERPUBLIC GROUP OF COMPANIES, INC.
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	13-1024020
Entity Address, Address Line One	909 Third Avenue,
Entity Address, City or Town	New York,
Entity Address, State or Province	NY
Entity Address, Postal Zip Code	10022
City Area Code	(212)
Local Phone Number	704-1200
Title of 12(b) Security	Common Stock, par value $0.10 per share
Trading Symbol	IPG
Security Exchange Name	NYSE
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		390,677,929
Entity Central Index Key	0000051644
Current Fiscal Year End Date	--12-31
Amendment Flag	false
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	FY
Entity Public Float			$ 6,500,000,000
ICFR Auditor Attestation Flag	true

Consolidated Statements of Operations - USD ($) shares in Millions, $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Statement [Abstract]
Net revenue	$ 2,284.4	$ 1,954.6	$ 1,853.4	$ 1,972.1	$ 2,433.0	$ 2,061.4	$ 2,125.9	$ 2,004.8	$ 8,064.5	$ 8,625.1	$ 8,031.6
Billable expenses	265.6	170.9	172.3	387.7	468.8	376.7	394.3	356.4	996.5	1,596.2	1,682.8
Total revenue	2,550.0	2,125.5	2,025.7	2,359.8	2,901.8	2,438.1	2,520.2	2,361.2	9,061.0	10,221.3	9,714.4
OPERATING EXPENSES:
Salaries and related expenses	1,346.2	1,269.9	1,306.1	1,422.8	1,432.1	1,334.4	1,381.2	1,421.1	5,345.0	5,568.8	5,298.3
Office and other direct expenses	364.8	307.9	317.0	378.2	419.7	367.9	387.3	389.2	1,367.9	1,564.1	1,355.1
Billable expense	265.6	170.9	172.3	387.7	468.8	376.7	394.3	356.4	996.5	1,596.2	1,682.8
Cost of services	1,976.6	1,748.7	1,795.4	2,188.7	2,320.6	2,079.0	2,162.8	2,166.7	7,709.4	8,729.1	8,336.2
Selling, General and Administrative Expense	22.4	9.9	4.1	22.4	24.5	9.8	18.1	41.4	58.8	93.8	166.5
Depreciation and amortization	73.7	71.0	73.1	72.8	65.4	69.0	73.0	71.1	290.6	278.5	202.9
Restructuring Charges	253.9	47.3	112.6	0.0	0.0	0.0	2.1	31.8	413.8	33.9	0.0
Total operating expenses	2,326.6	1,876.9	1,985.2	2,283.9	2,410.5	2,157.8	2,256.0	2,311.0	8,472.6	9,135.3	8,705.6
OPERATING INCOME	223.4	248.6	40.5	75.9	491.3	280.3	264.2	50.2	588.4	1,086.0	1,008.8
EXPENSES AND OTHER INCOME:
Interest expense									(192.2)	(199.3)	(123.0)
Interest income									29.5	34.5	21.8
Other expense, net	(9.8)	(11.3)	(21.5)	(21.8)	(24.8)	(7.4)	(3.8)	(6.9)	(64.4)	(42.9)	(69.6)
Total (expenses) and other income	(49.8)	(56.0)	(65.4)	(55.9)	(63.5)	(47.6)	(47.7)	(48.9)	(227.1)	(207.7)	(170.8)
Income before income taxes									361.3	878.3	838.0
Provision for income taxes	58.1	(86.3)	19.0	17.2	86.1	64.6	43.6	10.5	8.0	204.8	199.2
Income of consolidated companies									353.3	673.5	638.8
Equity in net (loss) income of unconsolidated affiliates									0.9	0.4	(1.1)
NET INCOME	$ 117.0	$ 278.5	$ (43.9)	$ 2.6	$ 342.2	$ 168.4	$ 172.8	$ (9.5)	354.2	673.9	637.7
Net Income (Loss) Attributable to Nonredeemable Noncontrolling Interest									(3.1)	(17.9)	(18.8)
Net Income (Loss) Attributable to Parent									$ 351.1	$ 656.0	$ 618.9
Earnings per share available to IPG common stockholders:
Earnings per share, Basic	$ 0.29	$ 0.72	$ (0.12)	$ 0.01	$ 0.85	$ 0.43	$ 0.44	$ (0.02)	$ 0.90	$ 1.70	$ 1.61
Earnings per share, Diluted	$ 0.28	$ 0.71	$ (0.12)	$ 0.01	$ 0.84	$ 0.42	$ 0.43	$ (0.02)	$ 0.89	$ 1.68	$ 1.59
Weighted-average number of common shares outstanding:
Weighted-average number of common shares outstanding, Basic									389.4	386.1	383.3
Weighted-average number of common shares outstanding, Diluted									393.2	391.2	389.0

Consolidated Statements of Comprehensive Income - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Statement of Comprehensive Income [Abstract]
NET INCOME	$ 354.2	$ 673.9	$ 637.7
Foreign Currency Translation:
Foreign currency translation adjustments	39.4	11.3	(149.6)
Reclassification adjustments recognized in net income	20.0	6.7	15.7
Foreign currency translation, net of tax	59.4	18.0	(133.9)
Derivatives instruments:
Changes in fair value of derivative instruments	11.3	0.0	0.0
Recognition of previously unrealized losses included in net income	2.4	2.3	2.2
Income tax effect	(3.4)	(0.5)	(0.7)
Derivative instruments, net of tax	10.3	1.8	1.5
Defined benefit pension and other postretirement plans:
Net actuarial (losses) gains for the period	(29.2)	(14.8)	12.6
Other Comprehensive (Income) Loss, Defined Benefit Plan, Reclassification Adjustment from AOCI, before Tax	7.4	6.7	7.5
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Gain (Loss) Due to Settlement and Curtailment	(0.1)	0.0	(1.0)
Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Other, before Tax	(3.3)	(2.5)	(1.0)
Income tax effect	4.6	1.2	(1.8)
Defined benefit pension and other postretirement plans, net of tax	(20.6)	(9.4)	16.3
Other comprehensive income (loss), net of tax	49.1	10.4	(116.1)
Total comprehensive income	403.3	684.3	521.6
Less: comprehensive income attributable to noncontrolling interests	2.4	17.2	16.0
Comprehensive Income Attributable to IPG	$ 400.9	$ 667.1	$ 505.6

Consolidated Balance Sheets - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019	Jan. 01, 2019	Dec. 31, 2018	Oct. 01, 2018	Dec. 31, 2017
ASSETS:
Cash and cash equivalents	$ 2,509.0	$ 1,192.2			$ 13.3
Accounts receivable, net of allowance of $98.3 and $40.2, respectively	4,646.4	5,209.2			112.9
Accounts receivable, billable to clients	1,820.7	1,934.1			8.3
Assets held for sale	0.8	22.8
Other current assets	390.7	412.4			28.2
Total current assets	9,367.6	8,770.7
Property and equipment, net of accumulated depreciation of $1,133.9 and $1,116.4 respectively	690.3	778.1			159.7
Deferred income taxes	302.0	252.1
Goodwill	4,945.5	4,894.4		$ 4,875.9	1,110.8
Other intangible assets	933.6	1,014.3
Operating Lease, Right-of-Use Asset	1,379.3	1,574.4	$ 1,421.1
Other non-current assets	424.4	467.9			8.3
TOTAL ASSETS	18,042.7	17,751.9
LIABILITIES:
Accounts payable	7,269.7	7,205.4
Accrued liabilities	832.4	742.8
Contract liabilities	657.8	585.6			23.2
Short-term borrowings	48.0	52.4
Current portion of long-term debt	502.5	502.0
Operating Lease, Liability, Current	268.5	267.2
Liabilities held for sale	1.6	65.0
Total current liabilities	9,580.5	9,420.4
Long-term debt	2,915.8	2,771.9
Operating Lease, Liability, Noncurrent	1,441.0	1,429.6
Deferred compensation	413.2	425.0
Other non-current liabilities	655.2	714.7			$ 0.8
TOTAL LIABILITIES	15,005.7	14,761.6
Redeemable noncontrolling interests	93.1	164.7		167.9		$ 252.1
STOCKHOLDERS' EQUITY:
Common stock, $0.10 par value, shares authorized: 800.0 shares issued: 2020 - 390.9; 2019 - 387.0 shares outstanding: 2020 - 390.9; 2019 - 387.0	39.0	38.7
Additional paid-in capital	1,099.3	977.3
Retained earnings	2,636.9	2,689.9
Accumulated other comprehensive loss, net of tax	(880.2)	(930.0)		(941.1)
Total IPG stockholders' equity	2,895.0	2,775.9
Noncontrolling interests	48.9	49.7
TOTAL STOCKHOLDERS' EQUITY	2,943.9	2,825.6		$ 2,432.8		$ 2,246.3
TOTAL LIABILITIES AND EQUITY	$ 18,042.7	$ 17,751.9

Consolidated Balance Sheets (Parenthetical) - USD ($) shares in Millions, $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Statement of Financial Position [Abstract]
Allowance for doubtful accounts	$ 98.3	$ 40.2
Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment	$ 1,133.9	$ 1,116.4
Common stock, par value	$ 0.10	$ 0.10
Common stock, shares authorized	800.0	800.0
Common stock, shares issued	390.9	387.0
Common stock, shares outstanding	390.9	387.0
Treasury stock, shares	0.0	0.0

Consolidated Statements of Cash Flows - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
CASH FLOWS FROM OPERATING ACTIVITIES:
NET INCOME	$ 354.2	$ 673.9	$ 637.7
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	290.6	278.5	202.9
Non-cash restructuring charges	265.6	11.7	0.0
Amortization of restricted stock and other non-cash compensation	67.0	80.2	82.2
Net losses on sales of businesses	67.0	43.4	61.9
Provision for uncollectible receivables	59.5	10.1	6.5
Net amortization of bond discounts and deferred financing costs	11.4	9.3	6.5
Deferred income tax provision	(46.4)	9.7	14.1
Other	20.0	6.8	1.2
Changes in assets and liabilities, net of acquisitions and divestitures, providing (using) cash:
Accounts receivable	551.4	(111.2)	(603.8)
Accounts receivable, billable to clients	122.5	(38.7)	(209.5)
Other current assets	11.9	(27.2)	(67.2)
Accounts payable	(27.0)	546.0	428.7
Accrued liabilities	179.3	27.4	(24.2)
Contract liabilities	62.0	46.5	44.9
Change in operating lease right-of-use asset and lease liabilities	(192.6)	(9.4)
Other non-current assets and liabilities	(141.8)	(37.2)	(16.8)
Net cash provided by operating activities	1,847.2	1,529.2	565.1
CASH FLOWS FROM INVESTING ACTIVITIES:
Acquisitions, net of cash acquired	4.9	0.6	2,309.8
Capital expenditures	167.5	198.5	177.1
Other investing activities	(43.8)	37.4	(4.6)
Net cash used in investing activities	(216.2)	(161.7)	(2,491.5)
CASH FLOWS FROM FINANCING ACTIVITIES:
Repayments of long-term debt	(503.7)	(403.3)	(104.8)
Common stock dividends	(398.1)	(363.1)	(322.1)
Acquisition-related payments	(46.6)	(15.8)	(33.7)
Tax payments for employee shares withheld	(22.3)	(22.4)	(29.2)
Distributions to noncontrolling interests	(19.5)	(21.6)	(16.9)
Proceeds from Long-term Debt	646.2	0.0	2,494.2
Exercise of stock options	6.5	4.3	15.5
Net increase (decrease) in short-term borrowings	1.5	(19.8)	(17.5)
Repurchases of common stock	0.0	0.0	(117.1)
Other financing activities	(10.2)	(1.3)	(15.2)
Net cash (used in) provided by financing activities	(346.2)	(843.0)	1,853.2
Effect of foreign exchange rate changes on cash, cash equivalents and restricted cash	31.0	(6.0)	(47.3)
Net increase (decrease) in cash, cash equivalents and restricted cash	1,315.8	518.5	(120.5)
Cash, cash equivalents and restricted cash at beginning of period	1,195.7	677.2	797.7
Cash, cash equivalents and restricted cash at end of period	$ 2,511.5	$ 1,195.7	$ 677.2

Consolidated Statements of Stockholders' Equity - USD ($) shares in Millions, $ in Millions	Total	Common Stock, Shares Issued [Member]	Common Stock	Additional Paid-In Capital	Retained Earnings (Accumulated Deficit)	Accumulated Other Comprehensive Loss, Net of Tax	Treasury Stock	Total IPG Stockholders' Equity	Noncontrolling Interests	Cumulative Effect, Period of Adoption, Adjustment	Cumulative Effect, Period of Adoption, Adjustment Retained Earnings (Accumulated Deficit)	Cumulative Effect, Period of Adoption, Adjustment Total IPG Stockholders' Equity
Common stock, shares issued		386.2
Balance at Dec. 31, 2017	$ 2,246.3		$ 38.6	$ 955.2	$ 2,104.5	$ (827.8)	$ (59.0)	$ 2,211.5	$ 34.8
Net Income (Loss) Attributable to Parent	618.9
NET INCOME	637.7				618.9			618.9
Net Income (Loss) Attributable to Nonredeemable Noncontrolling Interest	18.8								18.8
Other comprehensive income	(116.1)					(113.3)		(113.3)	(2.8)
Reclassifications related to redeemable noncontrolling interests	2.4							0.0	2.4
Distributions to noncontrolling interests	(16.9)								(16.9)
Change in redemption value of RNCI	42.9			41.8	1.1			42.9
Repurchases of common stock	(117.1)						(117.1)	(117.1)
Retirement of treasury stock, shares			(8.1)
Retirement of treasury stock	0.0		$ (0.8)	(175.3)			176.1	0.0
Common stock dividends	(322.1)				(322.1)			(322.1)
Stock-based compensation, shares			4.8
Shares Issued, Value, Share-based Payment Arrangement, after Forfeiture	87.5		$ 0.5	87.0				87.5
Exercise of stock options, shares			1.9
Exercise of stock options, Value	15.7		$ 0.2	15.5				15.7
Shares withheld for taxes, shares			(1.2)
Shares withheld for taxes, value	(29.2)		$ (0.2)	(29.0)				(29.2)
Other	1.7			(0.7)	(2.3)			(1.6)	3.3
Balance at Dec. 31, 2018	2,432.8		$ 38.3	895.9	2,400.1	(941.1)	0.0	2,393.2	39.6	$ 1.2	$ 1.2	$ 1.2
Common stock, shares issued		383.6
Net Income (Loss) Attributable to Parent	656.0
NET INCOME	673.9				656.0			656.0
Net Income (Loss) Attributable to Nonredeemable Noncontrolling Interest	17.9								17.9
Other comprehensive income	10.4					11.1		11.1	(0.7)
Reclassifications related to redeemable noncontrolling interests	24.6			11.9				11.9	12.7
Distributions to noncontrolling interests	(21.6)								(21.6)
Change in redemption value of RNCI	(0.2)				(0.2)			(0.2)
Common stock dividends	(363.1)				(363.1)			(363.1)
Stock-based compensation, shares			3.8
Shares Issued, Value, Share-based Payment Arrangement, after Forfeiture	89.1		$ 0.4	88.7				89.1
Exercise of stock options, shares			0.6
Exercise of stock options, Value	4.3		$ 0.1	4.2				4.3
Shares withheld for taxes, shares			(1.0)
Shares withheld for taxes, value	(22.4)		$ (0.1)	(22.3)				(22.4)
Other	(3.4)			1.1	(4.1)			(5.2)	1.8
Balance at Dec. 31, 2019	$ 2,825.6		38.7	977.3	2,689.9	(930.0)	$ 0.0	2,775.9	49.7	$ (6.6)	$ (6.6)	$ (6.6)
Common stock, shares issued	387.0	387.0
Net Income (Loss) Attributable to Parent	$ 351.1				351.1			351.1
NET INCOME	354.2
Net Income (Loss) Attributable to Nonredeemable Noncontrolling Interest	3.1								3.1
Other comprehensive income	49.1					49.8		49.8
Other Comprehensive Income (Loss), Tax, Portion Attributable to Noncontrolling Interest									(0.7)
Reclassifications related to redeemable noncontrolling interests	23.3			6.4				6.4	16.9
Distributions to noncontrolling interests	(19.5)								(19.5)
Change in redemption value of RNCI	46.2			41.2	5.0			46.2
Common stock dividends	(402.5)				(402.5)			(402.5)
Stock-based compensation, shares		4.4
APIC, Share-based Payment Arrangement, Increase for Cost Recognition	81.2		0.4	80.8				81.2
Exercise of stock options, shares		0.6
Exercise of stock options, Value	7.2		0.1	7.1				7.2
Shares withheld for taxes, shares		(1.1)
Shares withheld for taxes, value	(22.4)		(0.2)	(22.2)				(22.4)
Other	(8.1)			(8.7)				(8.7)	0.6
Balance at Dec. 31, 2020	$ 2,943.9		$ 39.0	$ 1,099.3	$ 2,636.9	$ (880.2)		$ 2,895.0	$ 48.9
Common stock, shares issued	390.9	390.9

Revenue Income Statement (Details) - USD ($) shares in Millions, $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Net revenue	$ 2,284.4	$ 1,954.6	$ 1,853.4	$ 1,972.1	$ 2,433.0	$ 2,061.4	$ 2,125.9	$ 2,004.8	$ 8,064.5	$ 8,625.1	$ 8,031.6
Billable expenses	265.6	170.9	172.3	387.7	468.8	376.7	394.3	356.4	996.5	1,596.2	1,682.8
Total revenue	2,550.0	2,125.5	2,025.7	2,359.8	2,901.8	2,438.1	2,520.2	2,361.2	9,061.0	10,221.3	9,714.4
OPERATING EXPENSES:
Salaries and related expenses	1,346.2	1,269.9	1,306.1	1,422.8	1,432.1	1,334.4	1,381.2	1,421.1	5,345.0	5,568.8	5,298.3
Office and other direct expenses	364.8	307.9	317.0	378.2	419.7	367.9	387.3	389.2	1,367.9	1,564.1	1,355.1
Billable expense	265.6	170.9	172.3	387.7	468.8	376.7	394.3	356.4	996.5	1,596.2	1,682.8
Cost of services	1,976.6	1,748.7	1,795.4	2,188.7	2,320.6	2,079.0	2,162.8	2,166.7	7,709.4	8,729.1	8,336.2
Selling, General and Administrative Expense	22.4	9.9	4.1	22.4	24.5	9.8	18.1	41.4	58.8	93.8	166.5
Depreciation and amortization	73.7	71.0	73.1	72.8	65.4	69.0	73.0	71.1	290.6	278.5	202.9
Total operating expenses	2,326.6	1,876.9	1,985.2	2,283.9	2,410.5	2,157.8	2,256.0	2,311.0	8,472.6	9,135.3	8,705.6
Operating Income (Loss)	223.4	248.6	40.5	75.9	491.3	280.3	264.2	50.2	588.4	1,086.0	1,008.8
EXPENSES AND OTHER INCOME:
Interest Expense									(192.2)	(199.3)	(123.0)
Interest income									29.5	34.5	21.8
Other expense, net	(9.8)	(11.3)	(21.5)	(21.8)	(24.8)	(7.4)	(3.8)	(6.9)	(64.4)	(42.9)	(69.6)
Total (expenses) and other income	(49.8)	(56.0)	(65.4)	(55.9)	(63.5)	(47.6)	(47.7)	(48.9)	(227.1)	(207.7)	(170.8)
Income before income taxes									361.3	878.3	838.0
Provision for income taxes	58.1	(86.3)	19.0	17.2	86.1	64.6	43.6	10.5	8.0	204.8	199.2
Income of consolidated companies									353.3	673.5	638.8
Equity in net (loss) income of unconsolidated affiliates									0.9	0.4	(1.1)
NET INCOME	$ 117.0	$ 278.5	$ (43.9)	$ 2.6	$ 342.2	$ 168.4	$ 172.8	$ (9.5)	354.2	673.9	637.7
Net Income (Loss) Attributable to Parent									$ 351.1	$ 656.0	$ 618.9
Earnings per share, Basic	$ 0.29	$ 0.72	$ (0.12)	$ 0.01	$ 0.85	$ 0.43	$ 0.44	$ (0.02)	$ 0.90	$ 1.70	$ 1.61
Earnings per share, Diluted	$ 0.28	$ 0.71	$ (0.12)	$ 0.01	$ 0.84	$ 0.42	$ 0.43	$ (0.02)	$ 0.89	$ 1.68	$ 1.59
Weighted-average number of common shares outstanding, Basic									389.4	386.1	383.3
Weighted-average number of common shares outstanding, Diluted									393.2	391.2	389.0

Revenue Balance Sheet (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Oct. 01, 2018	Dec. 31, 2017
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Cash and cash equivalents	$ 2,509.0	$ 1,192.2		$ 13.3
Accounts receivable, net of allowance of $98.3 and $40.2, respectively	4,646.4	5,209.2		112.9
Accounts receivable, billable to clients	1,820.7	1,934.1		8.3
Assets held for sale	0.8	22.8
Other current assets	390.7	412.4		28.2
Assets, Current	9,367.6	8,770.7
Deferred income taxes	302.0	252.1
Property, Plant and Equipment, Net	690.3	778.1		159.7
Goodwill	4,945.5	4,894.4	$ 4,875.9	1,110.8
Other intangible assets	933.6	1,014.3
Other non-current assets	424.4	467.9		8.3
Assets	18,042.7	17,751.9
Accounts Payable, Current	7,269.7	7,205.4
Accrued Liabilities, Current	832.4	742.8
Contract liabilities	657.8	585.6		23.2
Short-term borrowings	48.0	52.4
Current portion of long-term debt	502.5	502.0
Liabilities held for sale	1.6	65.0
Liabilities, Current	9,580.5	9,420.4
Long-term debt	2,915.8	2,771.9
Deferred compensation	413.2	425.0
Other non-current liabilities	655.2	714.7		$ 0.8
Liabilities	15,005.7	14,761.6
Redeemable noncontrolling interests	93.1	164.7	167.9		$ 252.1
STOCKHOLDERS' EQUITY:
Common stock, $0.10 par value, shares authorized: 800.0 shares issued: 2020 - 390.9; 2019 - 387.0 shares outstanding: 2020 - 390.9; 2019 - 387.0	39.0	38.7
Additional Paid in Capital	1,099.3	977.3
Retained Earnings (Accumulated Deficit)	2,636.9	2,689.9
Accumulated other comprehensive loss, net of tax	(880.2)	(930.0)	(941.1)
Stockholders' Equity Attributable to Parent	2,895.0	2,775.9
Stockholders' Equity Attributable to Noncontrolling Interest	48.9	49.7
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest	2,943.9	2,825.6	$ 2,432.8		$ 2,246.3
Liabilities and Equity	$ 18,042.7	$ 17,751.9

Revenue Statement of Cash Flows (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
NET INCOME	$ 117.0	$ 278.5	$ (43.9)	$ 2.6	$ 342.2	$ 168.4	$ 172.8	$ (9.5)	$ 354.2	$ 673.9	$ 637.7
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization									290.6	278.5	202.9
Provision for uncollectible receivables									59.5	10.1	6.5
Amortization of restricted stock and other non-cash compensation									67.0	80.2	82.2
Net amortization of bond discounts and deferred financing costs									11.4	9.3	6.5
Deferred income tax provision									(46.4)	9.7	14.1
Net losses on sales of businesses	(15.2)	$ (8.6)	$ (19.9)	$ (23.3)	(23.9)	$ (7.7)	$ (3.2)	$ (8.6)	67.0	43.4	61.9
Other									20.0	6.8	1.2
Net Cash Provided by (Used in) Investing Activities [Abstract]
Accounts receivable									551.4	(111.2)	(603.8)
Accounts receivable, billable to clients									122.5	(38.7)	(209.5)
Other current assets									11.9	(27.2)	(67.2)
Accounts payable									(27.0)	546.0	428.7
Accrued liabilities									179.3	27.4	(24.2)
Contract liabilities									62.0	46.5	44.9
Other non-current assets and liabilities									(141.8)	(37.2)	(16.8)
Net cash provided by operating activities									1,847.2	1,529.2	565.1
Net cash used in investing activities									(216.2)	(161.7)	(2,491.5)
Net cash (used in) provided by financing activities									(346.2)	(843.0)	1,853.2
Effect of foreign exchange rate changes on cash, cash equivalents and restricted cash									31.0	(6.0)	(47.3)
Net increase (decrease) in cash, cash equivalents and restricted cash									1,315.8	518.5	(120.5)
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents	$ 2,511.5				$ 1,195.7				$ 2,511.5	$ 1,195.7	$ 677.2	$ 797.7

Revenue Contract Balances (Details) - USD ($) $ in Millions	3 Months Ended		12 Months Ended
Revenue Contract Balances (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2020	Dec. 31, 2019
Accounts receivable, net of allowance of $98.3 and $40.2, respectively	$ 4,646.4	$ 5,209.2	$ 4,646.4	$ 5,209.2
Accounts receivable, billable to clients	1,820.7	1,934.1	1,820.7	1,934.1
Contract with Customer, Asset, after Allowance for Credit Loss	51.8	63.0	51.8	63.0
Contract liabilities	657.8	585.6	657.8	585.6
Revenue, remaining performance obligation, amount	654.0		654.0
Net revenue	$ 2,284.4	$ 2,433.0	$ 8,064.5	$ 8,625.1

- Definition

Amount, excluding tax collected from customer, of revenue from satisfaction of performance obligation by transferring promised good or service to customer. Tax collected from customer is tax assessed by governmental authority that is both imposed on and concurrent with specific revenue-producing transaction, including, but not limited to, sales, use, value added and excise.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 30
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e8906-108599

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 40
-URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e9031-108599

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 41
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e9038-108599

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 32
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e8933-108599

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 32
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e8933-108599

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 4
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=121604090&loc=SL49130543-203045

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 22
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e8736-108599

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 22
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e8736-108599

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 42
-URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e9054-108599

Reference 10: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=121604090&loc=SL49130545-203045

Reference 11: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 924
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SAB Topic 11.L)
-URI http://asc.fasb.org/extlink&oid=6472922&loc=d3e499488-122856

+ Details

Supplemental Cash Flow Information (Details) - USD ($)
$ in Millions

12 Months Ended

Dec. 31, 2020

Dec. 31, 2019

Dec. 31, 2018

Supplemental Cash Flow Information [Abstract]

Interest Paid, Excluding Capitalized Interest, Operating Activities

$ 182.2

$ 192.7

$ 88.7

Change in operating lease right-of-use asset and lease liabilities

192.6

9.4

Cash paid for income taxes, net of refunds

^[1]

89.1

150.2

207.9

Tax refunds

124.2

92.6

24.3

Restructuring Charges

413.8

33.9

$ 0.0

Supplemental Cash Flow Elements [Abstract]

Lease restructuring costs

209.9

8.7

Change in operating lease right-of-use asset and lease liabilities

192.6

9.4

Net cash activities for operating lease right-of-use asset and lease liabilities included in Other non-current assets and liabilities under Operating Activities

$ 17.3

$ 0.7

[1]	Refunds of $124.2, $92.6 and $24.3 were received for the years ended December 31, 2020, 2019 and 2018, respectively.

Significant Accounting Policies (Notes)	12 Months Ended
Significant Accounting Policies (Notes)	Dec. 31, 2020
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	Summary of Significant Accounting Policies Business Description The Interpublic Group of Companies, Inc. and subsidiaries (the “Company,” “IPG,” “we,” “us” or “our”) is one of the world’s premier global advertising and marketing services companies. Our agencies create customized marketing programs for clients that range in scale from large global marketers to regional and local clients. Comprehensive global services are critical to effectively serve our multinational and local clients in markets throughout the world, as they seek to build brands, increase sales of their products and services and gain market share. Principles of Consolidation The Consolidated Financial Statements include the accounts of the Company and its consolidated subsidiaries, some of which are not wholly owned. Investments in companies over which we do not have control, but have the ability to exercise significant influence, are accounted for using the equity method of accounting. Investments in companies over which we have neither control nor have the ability to exercise significant influence are recorded at cost, less any impairment, adjusted for subsequent observable price changes. All intercompany accounts and transactions have been eliminated in consolidation. We have consolidated certain entities meeting the definition of variable interest entities, and the inclusion of these entities does not have a material impact on our Consolidated Financial Statements. Basis of Presentation Cost of services is comprised of the expenses of our revenue-producing operating segments including salaries and related expenses, office and other direct expenses and billable expenses, as well as an allocation of the centrally managed expenses from Corporate and other. Office and other direct expenses include rent expense, professional fees, certain expenses incurred by our staff in servicing our clients and other costs directly attributable to client engagements. Selling, general and administrative expenses are primarily the unallocated expenses from Corporate and other, as disclosed further in Note 15, excluding depreciation and amortization. Depreciation and amortization of the fixed assets and intangible assets of the Company is disclosed as a separate operating expense. Restructuring charges relate to the Company's implementation of a cost initiative to better align our cost structure with our revenue, as discussed further in Note 11. Reclassifications Certain reclassifications and immaterial changes have been made to prior-period financial statements to conform to the current-period presentation. Segment information for the prior period has been recast to conform to the current-period presentation. Use of Estimates The preparation of financial statements in conformity with accounting principles generally accepted in the United States of America (“U.S. GAAP”) requires us to make judgments, assumptions and estimates that affect the amounts of assets and liabilities, the disclosure of contingent assets and liabilities at the reporting date and the reported amounts of revenues and expenses during the reporting period. Actual results could differ from these estimates and assumptions. Revenue Recognition Our revenues are primarily derived from the planning and execution of multi-channel advertising and communications, marketing services, including public relations, meeting and event production, sports and entertainment marketing, corporate and brand identity, strategic marketing consulting, and providing marketing data and technology services around the world. Most of our client contracts are individually negotiated and, accordingly, the terms of client engagements and the basis on which we earn fees and commissions vary significantly. Our contracts generally provide for termination by either party on relatively short notice, usually 30 to 90 days, although our data management contracts typically have non-cancelable terms of more than one year. Our payment terms vary by client, and the time between invoicing date and due date is typically not significant. We generally have the legally enforceable right to payment for all services provided through the end of the contract or termination date. We recognize revenue when we determine our customer obtains control of promised goods or services, in an amount that reflects the consideration which we expect to receive in exchange for those goods or services. To determine revenue recognition, we perform the following five steps: (i) identify the contract(s) with a customer; (ii) identify the performance obligations in the contract; (iii) determine the transaction price; (iv) allocate the transaction price to the performance obligations in the contract; and (v) recognize revenue as or when we satisfy the performance obligation. We only apply the five-step model to contracts when it is probable that IPG will collect the consideration it is entitled to in exchange for the goods or services it transfers to the customer. At contract inception, we assess the goods or services promised within each contract and determine those that are distinct performance obligations. We then assess whether we act as an agent or a principal for each identified performance obligation and include revenue within the transaction price for third-party costs when we determine that we act as principal. We typically do not capitalize costs to obtain a contract as these amounts would generally be recognized over a period of one year or less. Net revenue, primarily consisting of fees, commissions and performance incentives, represents the amount of our gross billings excluding billable expenses charged to a client. Generally, our compensation is based on a negotiated fixed price, rate per hour, a retainer, commission or volume. The majority of our fees are recognized over time as services are performed, either utilizing a function of hours incurred and rates per hour, as compared to periodically updated estimates to complete, or ratably over the term of the contract. For certain less-frequent commission-based contracts which contain clauses allowing our clients to terminate the arrangement at any time for no compensation, revenue is recognized at a point in time, typically the date of broadcast or publication. We report revenue net of taxes assessed by governmental authorities that are directly imposed on our revenue-producing transactions. Contractual arrangements with clients may also include performance incentive provisions designed to link a portion of our revenue to our performance relative to mutually agreed-upon qualitative and/or quantitative metrics. Performance incentives are treated as variable consideration which is estimated at contract inception and included in revenue based on the most likely amount earned out of a range of potential outcomes. Our estimates are based on a combination of historical award experience, anticipated performance and our best judgment. These estimates are updated on a periodic basis and are not expected to result in a reversal of a significant amount of the cumulative revenue recognized. The predominant component of billable expenses are third-party vendor costs incurred for performance obligations where we have determined that we are acting as principal. These third-party expenses are generally billed back to our clients. Billable expenses also includes incidental costs incurred in the performance of our services including airfare, mileage, hotel stays, out-of-town meals and telecommunication charges. We record these billable expenses within total revenue with a corresponding offset to operating expenses. In international markets, we may receive rebates or credits from vendors based on transactions entered into on behalf of clients. Rebates and credits are remitted back to our clients in accordance with our contractual requirements or may be retained by us based on the terms of a particular client contract and local law. Amounts owed back to clients are recorded as a liability and amounts retained by us are recorded as revenue when earned. In certain international markets, our media contracts may allow clients to terminate our arrangement at any time for no compensation to the extent that media has not yet run. For those contracts, we do not recognize revenue until the media runs which is the point in time at which we have a legally enforceable right to compensation. Performance Obligations Our client contracts may include various goods and services that are capable of being distinct, are distinct within the context of the contract and are therefore accounted for as separate performance obligations. We allocate revenue to each performance obligation in the contract at inception based on its relative standalone selling price. Our advertising businesses include a wide range of services that involve the creation of an advertising idea, concept, campaign, or marketing strategy in order to promote the client’s brand ("creative services"), and to act as an agent to facilitate the production of advertisements by third-party suppliers ("production services”). Our clients can contract us to perform one or both of these services, as they can derive stand-alone benefit from each. Production services can include formatting creative material for different media and communication mediums including digital, large-scale reproduction such as printing and adaptation services, talent engagement and acquisition, television and radio production, and outdoor billboard production. Our contracts that include both services are typically explicit in the description of which activities constitute the creative advertising services and those that constitute the production services. Both the creative and production services are sold separately, the client can derive utility from each service on its own, we do not provide a significant service of integrating these activities into a bundle, the services do not significantly modify one another, and the services are not highly interrelated or interdependent. As such, we typically identify two performance obligations in the assessment of our advertising contracts. Our media businesses include services to formulate strategic media plans ("media planning services") and to act as an agent to purchase media (e.g. television and radio spots, outdoor advertising, digital banners, etc.) from vendors on our clients' behalf ("media buying services"). Our contracts that include both services are typically explicit in the description of which activities constitute the planning services and those that constitute the buying services. Both the planning and buying services are sold separately, the client can derive utility from each service on its own, we do not provide a significant service of integrating these activities into a bundle, the services do not significantly modify one another, and the services are not highly interrelated or interdependent. As such, we typically identify two performance obligations in the assessment of our media contracts. Our events businesses include creative services related to the conception and planning of custom marketing events as well as activation services which entail the carrying out of the event, including, but not limited to, set-up, design and staffing. Additionally, our public relations businesses include a broad range of services, such as strategic planning, social media strategy and the monitoring and development of communication strategies, among others. While our contracts in these businesses may include some or all of these services, we typically identify only one performance obligation in the assessment of our events and public relations contracts as we provide a significant service of integrating the individual services into a combined service for which the customer has contracted. Our data and technology services businesses include data management, data and data strategy, identity resolution, and measurement and analytics products and services. While our contracts in these businesses may include some or all of these services, we typically identify each product and service as an individual performance obligation. We have elected not to disclose information about remaining performance obligations that have original expected durations of one year or less. The majority of our contracts are for periods of one year or less with the exception of our data management contracts. Principal vs. Agent When a third-party is involved in the delivery of our services to the client, we assess whether or not we are acting as a principal or an agent in the arrangement. The assessment is based on whether we control the specified services at any time before they are transferred to the customer. We have determined that in our events and public relations businesses, we generally act as a principal as our agencies provide a significant service of integrating goods or services provided by third parties into the specified deliverable to our clients. In addition, we have determined that we are responsible for the performance of the third-party suppliers, which are combined with our own services, before transferring those services to the customer. We have also determined that we act as principal when providing creative services and media planning services, as we perform a significant integration service in these transactions. For performance obligations in which we act as principal, we record the gross amount billed to the customer within total revenue and the related incremental direct costs incurred as billable expenses. When a third-party is involved in the production of an advertising campaign and for media buying services, we have determined that we act as the agent and are solely arranging for the third-party suppliers to provide services to the customer. Specifically, we do not control the specified services before transferring those services to the customer, we are not primarily responsible for the performance of the third-party services, nor can we redirect those services to fulfill any other contracts. We do not have inventory risk or discretion in establishing pricing in our contracts with customers. For performance obligations for which we act as the agent, we record our revenue as the net amount of our gross billings less amounts remitted to third parties. Cash and Cash Equivalents Cash equivalents are highly liquid investments, which include certificates of deposit, government securities, commercial paper and time deposits with original maturities of three months or less at the time of purchase and are stated at estimated fair value, which approximates cost. Cash is maintained at multiple high-credit-quality financial institutions. Allowance for Expected Credit Losses We adopted Accounting Standards Codification Topic 326, Current Expected Credit Losses, on January 1, 2020 using the modified retrospective transition method. The allowance for credit losses on expected future uncollectible accounts receivable is estimated based on the aging of accounts receivable, reviews of client credit reports, industry trends and economic indicators, as well as reviews of recent payment history for specific customers. The estimate is based largely on a formula-driven calculation but is supplemented with economic indicators and knowledge of potential write-offs of specific client accounts. Accounts Receivable, Billable to Clients Accounts receivable, billable to clients are primarily comprised of production and media costs that have been incurred but have not yet been billed to clients, as well as fees that have been earned which have not yet been billed to clients. Unbilled amounts are presented in expenditures billable to clients regardless of whether they relate to our fees or production and media costs. A provision is made for unrecoverable costs as deemed appropriate. Accounts Payable Accounts payable includes all operating payables, including those related to all media and production costs. These payables are due within one year. Investments Equity investments with readily determinable fair values, other than those accounted for using the equity method of accounting, will be measured at fair value. We regularly review our investments to determine whether a significant event or change in circumstances has occurred that may impact the fair value of each investment, with changes to fair value recorded in earnings. We evaluate fair value based on specific information (valuation methodologies, estimates of appraisals, financial statements, etc.) in addition to quoted market price, if available. We consider all known quantitative and qualitative factors in determining if a decline in value of an investment has occurred. Derivatives We are exposed to market risk related to interest rates, foreign currency rates and certain balance sheet items. From time to time we enter into derivative instruments for risk management purposes, and not for speculative purposes. All derivative instruments are recorded at fair value on our balance sheet. Changes in fair value are immediately included in earnings if the derivatives are not designated as a hedge instrument or if the derivatives do not qualify as effective hedges. For derivatives designated as hedge instruments, we evaluate for hedge accounting both at inception and throughout the hedge period. If a derivative is designated as a fair value hedge, then changes in the fair value of the derivative are offset against the changes in the fair value of the underlying hedged item. If a derivative is designated as a cash flow hedge, then the changes in the fair value of the derivative are recognized as a component of accumulated other comprehensive income and subsequently reclassified to earnings in our Consolidated Statement of Operations in the same period as the underlying hedged transaction affects earnings. If a derivative is a net investment hedge, then the changes in the fair value of the derivative are recognized in other comprehensive income in the same period as the change in fair value of the underlying hedged foreign investment. Property and Equipment Furniture, equipment, leasehold improvements and buildings are stated at cost, net of accumulated depreciation. Furniture and equipment are depreciated generally using the straight-line method over the estimated useful lives of the related assets, which range from 3 to 7 years for furniture and equipment, 10 to 35 years for buildings and the shorter of the useful life or the remaining lease term for leasehold improvements. Land is stated at cost and is not depreciated. We capitalize certain internal and external costs incurred to acquire or create internal use software, principally related to our enterprise resource planning (“ERP”) systems. Our ERP systems are stated at cost, net of accumulated amortization, and are amortized using the straight-line method over 10 years. All other internal use computer software are stated at cost, net of accumulated amortization and are amortized using the straight-line method over the estimated useful lives of the related assets, which range from 3 to 7 years. Leases Effective January 1, 2019, we adopted Accounting Standards Codification Topic 842, Leases (ASC 842), using the modified retrospective transition method. As such, we recognized a right-of-use asset and a corresponding lease liability on our Consolidated Balance Sheet for virtually all of our leases with a term of more than twelve months. Consolidated financial statements for the year ended December 31, 2018 were not recast under the new standard. As an accounting policy, we have elected not to apply the recognition requirements to short-term leases, not to separate non-lease components from lease components, and have elected the package of transition provisions available for existing contracts, which allowed us to carry forward our historical assessments of (i) whether contracts are or contain leases, (ii) lease classification and (iii) initial direct costs. The adoption of ASC 842 resulted in operating lease right-of-use assets of $1,421.1 and operating lease liabilities of $1,544.4 as of January 1, 2019. As of December 31, 2020, we do not have a material amount of finance leases and the majority of our operating leases, for which we serve as the lessee, consist primarily of real-estate property for our offices around the world. Both the right-of-use asset and lease liability are measured at the present value of the future lease payments, with the asset being subject to adjustments such as initial direct costs, prepaid lease payments, and lease incentives. Many of our leases provide for renewal and/or termination options, as well as escalation clauses, which are also factored into our lease payments when appropriate. The discount rate used to measure the lease asset and liability is determined at the beginning of the lease term using the rate implicit in the lease, if readily determinable, or using the Company's collateralized credit-adjusted borrowing rate. Goodwill and Other Intangible Assets We account for our business combinations using the acquisition accounting method, which requires us to determine the fair value of net assets acquired and the related goodwill and other intangible assets. Determining the fair value of assets acquired and liabilities assumed requires management's judgment and involves the use of significant estimates, including projections of future cash inflows and outflows, discount rates, asset lives and market multiples. Considering the characteristics of advertising, specialized marketing and communication services companies, our acquisitions usually do not have significant amounts of tangible assets, as the principal asset we typically acquire is creative talent. As a result, a substantial portion of the purchase price is allocated to goodwill and other intangible assets. We review goodwill as of October 1st each year and whenever events or significant changes in circumstances indicate that the carrying value may not be recoverable. We evaluate the recoverability of goodwill at a reporting unit level. We have 12 reporting units that were subject to the 2020 annual impairment testing. Our annual impairment review as of October 1, 2020 did not result in an impairment charge for any of our reporting units. Intangible assets with indefinite useful lives are not amortized but are evaluated for impairment annually or more frequently if events or changes in circumstances indicate that impairment may exist. The Company first assesses qualitative factors to determine whether it is necessary to perform a quantitative impairment test for indefinite-lived intangible assets. Impairment exists if the fair value of the indefinite-lived intangible asset is less than the carrying value. Our annual impairment review as of October 1, 2020 did not result in an impairment charge for any of our intangible assets with indefinite useful lives. For reporting units not included in the qualitative assessment, or for any reporting units identified in the qualitative assessment as "more likely than not" that the fair value is less than its carrying value, the quantitative impairment test is performed. For our annual impairment test, we compare the respective fair value of our reporting units' equity to the carrying value of their net assets. The sum of the fair values of all our reporting units is also reconciled to our current market capitalization plus an estimated control premium. Goodwill allocated to a reporting unit whose fair value is equal to or greater than its carrying value is not impaired, and no further testing is required. Should the carrying amount for a reporting unit exceed its fair value, then the quantitative impairment test is failed and impaired goodwill is written down to its fair value with a charge to expense in the period the impairment is identified. The fair value of each reporting unit for 2020 and 2019 was estimated using a combination of the income approach, which incorporates the use of the discounted cash flow method, and the market approach, which incorporates the use of earnings and revenue multiples based on market data. We review intangible assets with definite lives subject to amortization whenever events or circumstances indicate that a carrying amount of an asset may not be recoverable. Recoverability of these assets is determined by comparing the carrying value of these assets to the estimated undiscounted future cash flows expected to be generated by these asset groups. These asset groups are impaired when their carrying value exceeds their fair value. Impaired intangible assets with definite lives subject to amortization are written down to their fair value with a charge to expense in the period the impairment is identified. Intangible assets with definite lives are amortized on a straight-line basis with estimated useful lives generally between 7 and 15 years. Events or circumstances that might require impairment testing include the loss of a significant client, the identification of other impaired assets within a reporting unit, loss of key personnel, the disposition of a significant portion of a reporting unit, significant decline in stock price or a significant adverse change in business climate or regulations. Foreign Currencies The functional currency of our foreign operations is generally their respective local currency. Assets and liabilities are translated at the exchange rates in effect at the balance sheet date, and revenues and expenses are translated at the average exchange rates during the period presented. The resulting translation adjustments are recorded as a component of accumulated other comprehensive loss in the stockholders’ equity section of our Consolidated Balance Sheets. Currency transaction gains or losses primarily arising from transactions in currencies other than the functional currency are included in office and general expenses. Foreign currency transactions resulted in a pre-tax gain of $1.2 for the year ended December 31, 2020, a pre-tax loss of $5.3 for the year ended December 31, 2019 and a pre-tax gain $5.6 in for the year ended December 31, 2018. We monitor the currencies of countries in which we operate in order to determine if the country should be considered a highly inflationary environment. A currency is determined to be highly inflationary when there is cumulative inflation of approximately 100% or more over a three-year period. If this occurs the functional currency of that country is changed to our reporting currency, the U.S. Dollar, and foreign exchange gains or losses are recognized on all monetary transactions, assets and liabilities in currencies other than the U.S. Dollar until the currency is no longer considered highly inflationary. Income Taxes The provision for income taxes includes U.S. federal, state, local and foreign taxes. Income taxes are accounted for under the liability method. Deferred tax assets and liabilities are recognized for the estimated future tax consequences of temporary differences between the financial statement carrying amounts and their respective tax bases. Deferred tax assets and liabilities are measured using enacted tax rates expected to apply to taxable income in the year in which the temporary differences are expected to be reversed. We evaluate the realizability of our deferred tax assets and establish a valuation allowance when it is “more likely than not” that all or a portion of the deferred tax assets will not be realized. We evaluate our tax positions using the “more likely than not” recognition threshold and then apply a measurement assessment to those positions that meet the recognition threshold. The factors used in assessing valuation allowances include all available evidence, such as past operating results, estimates of future taxable income and the feasibility of tax planning strategies. We have established tax reserves that we believe to be adequate in relation to the potential for additional assessments in each of the jurisdictions in which we are subject to taxation. We regularly assess the likelihood of additional tax assessments in those jurisdictions and adjust our reserves as additional information or events require. Redeemable Noncontrolling Interests Many of our acquisitions include provisions under which the noncontrolling equity owners can require us to purchase additional interests in a subsidiary at their discretion. Payments for these redeemable noncontrolling interests may be contingent on projected operating performance and satisfying other conditions specified in the related agreements. These payments are also subject to revision in accordance with the terms of the agreements. We record these redeemable noncontrolling interests in “mezzanine equity” in our Consolidated Balance Sheets. Each reporting period, redeemable noncontrolling interests are reported at their estimated redemption value, but not less than their initial fair value. Any adjustment to the redemption value above initial value prior to exercise will also impact retained earnings or additional paid-in capital (“APIC”), but will not impact net income. Adjustments as a result of currency translation will affect the redeemable noncontrolling interest balance, but do not impact retained earnings or additional paid-in capital. Earnings Per Share (“EPS”) Basic EPS available to IPG common stockholders equals net income available to IPG common stockholders divided by the weighted-average number of common shares outstanding for the applicable period. Diluted EPS equals net income available to IPG common stockholders divided by the weighted-average number of common shares outstanding, plus any additional common shares that would have been outstanding if potentially dilutive shares had been issued. Diluted EPS reflect the potential dilution that would occur if certain potentially dilutive securities were exercised. The potential issuance of common stock is assumed to occur at the beginning of the year (or at the time of issuance of the potentially dilutive instrument, if later) and the incremental shares are included using the treasury stock method. The proceeds utilized in applying the treasury stock method consist of the amount, if any, to be paid upon exercise and, as it relates to stock-based compensation, the amount of compensation cost attributed to future service not yet recognized. These proceeds are then assumed to be used to purchase common stock at the average market price of our stock during the period. The incremental shares (difference between the shares assumed to be issued and the shares assumed to be purchased), to the extent they would have been dilutive, are included in the denominator of the diluted EPS calculation. We may be required to calculate basic EPS using the two-class method as a result of our redeemable noncontrolling interests. To the extent that the redemption value increases and exceeds the then-current fair value of a redeemable noncontrolling interest, net income available to IPG common stockholders (used to calculate EPS) could be negatively impacted by that increase, subject to certain limitations. The partial or full recovery of any reductions to net income available to IPG common stockholders (used to calculate EPS) is limited to any cumulative prior-period reductions. For the years ended December 31, 2020, 2019 and 2018, there was no impact to EPS for adjustments related to our redeemable noncontrolling interests. Pension and Postretirement Benefits We have pension and postretirement benefit plans covering certain domestic and international employees. We use various actuarial methods and assumptions in determining our net pension and postretirement benefit costs and obligations, including the discount rate used to determine the present value of future benefits, expected long-term rate of return on plan assets and healthcare cost trend rates. The overfunded or underfunded status of our pension and postretirement benefit plans is recorded on our Consolidated Balance Sheet. Stock-Based Compensation Compensation costs related to share-based transactions, including employee stock options, are recognized in the Consolidated Financial Statements based on fair value. Stock-based compensation expense is generally recognized ratably over the requisite service period based on the estimated grant-date fair value, net of estimated forfeitures. Treasury Stock We account for repurchased common stock under the cost method and include such treasury stock as a component of our Consolidated Statements of Stockholders' Equity. Upon retirement, we reduce common stock for the par value of the shares being retired and the excess of the cost of the shares over par value as a reduction to APIC, to the extent there is APIC in the same class of stock, and any remaining amount to retained earnings. These retired shares remain authorized but unissued.During 2020 and 2019, there was no significant treasury stock activity due to the suspension of the share repurchase program, as disclosed further in Note 7. In October 2018, we retired 8.1 shares of our treasury stock, which resulted in a reduction in common stock of $0.8, treasury stock of $176.1 and APIC of $175.3.

Revenue (Notes)	12 Months Ended
Revenue (Notes)	Dec. 31, 2020
Revenue from Contract with Customer [Abstract]
Revenue from Contract with Customer [Text Block]	Contract assets are primarily comprised of contract incentives that are generally satisfied annually under the terms of our contracts and are transferred to accounts receivable when the right to payment becomes unconditional. Contract liabilities relate to advance consideration received from customers under the terms of our contracts primarily related to reimbursements of third-party expenses, whether we act as principal or agent, and to a lesser extent, periodic retainer fees, both of which are generally recognized shortly after billing. The majority of our contracts are for periods of one year or less with the exception of our data management contracts. For those contracts with a term of more than one year, we had approximately $654.0 of unsatisfied performance obligations as of December 31, 2020, which will be recognized as services are performed over the remaining contractual terms through 2026.

- Definition

The entire disclosure of revenue from contract with customer to transfer good or service and to transfer nonfinancial asset. Includes, but is not limited to, disaggregation of revenue, credit loss recognized from contract with customer, judgment and change in judgment related to contract with customer, and asset recognized from cost incurred to obtain or fulfill contract with customer. Excludes insurance and lease contracts.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-URI http://asc.fasb.org/topic&trid=49130388

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 10
-URI http://asc.fasb.org/extlink&oid=121604090&loc=SL49130551-203045

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 13
-Subparagraph (b)(2)
-URI http://asc.fasb.org/extlink&oid=121604090&loc=SL49130556-203045

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 12
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=121604090&loc=SL49130554-203045

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 9
-URI http://asc.fasb.org/extlink&oid=121604090&loc=SL49130550-203045

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 12
-Subparagraph (e)
-URI http://asc.fasb.org/extlink&oid=121604090&loc=SL49130554-203045

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 12
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=121604090&loc=SL49130554-203045

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 12
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=121604090&loc=SL49130554-203045

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 15
-URI http://asc.fasb.org/extlink&oid=121604090&loc=SL49130558-203045

Reference 10: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 12
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=121604090&loc=SL49130554-203045

+ Details

Leases (Notes)

12 Months Ended

Dec. 31, 2020

Leases [Abstract]

Lessee, Operating Leases [Text Block]

Leases

As of December 31, 2020 and 2019, the majority of our operating leases, for which we serve as the lessee, consist primarily of real-estate property for our offices around the world, and we do not have a material amount of finance leases. Both the right-of-use asset and lease liability are measured at the present value of the future lease payments, with the asset being subject to adjustments such as initial direct costs, prepaid lease payments, and lease incentives. Many of our leases provide for renewal and/or termination options, as well as escalation clauses, which are also factored into our lease payments when appropriate. As of December 31, 2020, our leases have remaining lease terms of 1 year to 19 years. The discount rate used to measure the lease asset and liability is determined at the beginning of the lease term using the rate implicit in the lease, if readily determinable, or using the Company's collateralized credit-adjusted borrowing rate.

The following tables present information on our operating leases for the full years of 2020 and 2019.


	Years ended December 31,
	2020			2019
Operating lease cost	$	318.5		$	325.2
Short-term lease cost	10.6			13.8
Sublease income	(15.8)			(12.9)
Total lease cost	$	313.3		$	326.1

Cash paid related to operating lease liabilities	$	335.7		$	334.1
Right-of-use assets obtained in exchange for lease liabilities	$	274.4		$	422.8

	As of December 31,
	2020			2019
Weighted-average remaining lease term	Eight years			Eight years
Weighted-average discount rate	4.00		%	4.26		%

Our future payments of our operating leases as of December 31, 2020 are listed in the table below.


Period	Net Rent
2021	$	322.9
2022	302.6
2023	241.2
2024	212.2
2025	194.7
Thereafter	735.2
Total future lease payments	2,008.8
Less: imputed interest	299.3
Present value of future lease payments	1,709.5
Less: current portion of operating leases	268.5
Non-current operating leases	$	1,441.0

As of December 31, 2020, we had additional operating leases that had not yet commenced with future lease payments of approximately $52.0 commencing in 2021 with lease terms of 1 to 10 years.

Debt and Credit Agreements (Notes)

12 Months Ended

Dec. 31, 2020

Debt Disclosure [Abstract]

Debt Disclosure [Text Block]

Long-Term Debt

A summary of the carrying amounts of our long-term debt is listed below.


	Effective Interest Rate		December 31,
			2020 1		2019 1
3.50% Senior Notes due 2020	3.89	%	$	—	$	498.5
3.75% Senior Notes due 2021 (less unamortized discount and issuance costs of $0.1 and $0.8, respectively)	3.98	%	499.1		497.9
4.00% Senior Notes due 2022 (less unamortized discount and issuance costs of $0.4 and $0.3, respectively)	4.13	%	249.3		248.7
3.75% Senior Notes due 2023 (less unamortized discount and issuance costs of $0.3 and $0.9, respectively)	4.32	%	498.8		498.2
4.20% Senior Notes due 2024 (less unamortized discount and issuance costs of $0.3 and $1.4, respectively)	4.24	%	498.3		497.8
4.65% Senior Notes due 2028 (less unamortized discount and issuance costs of $1.3 and $3.5, respectively)	4.78	%	495.2		494.6
4.75% Senior Notes due 2030 (less unamortized discount and issuance costs of $3.5 and $5.7, respectively)	4.92	%	640.8		—
5.40% Senior Notes due 2048 (less unamortized discount and issuance costs of $2.7 and $5.2, respectively)	5.48	%	492.1		491.9
Other notes payable and capitalized leases			44.7		46.3
Total long-term debt			3,418.3		3,273.9
Less: current portion			502.5		502.0
Long-term debt, excluding current portion			$	2,915.8	$	2,771.9

1See Note 13 for information on the fair value measurement of our long-term debt.

Annual maturities are scheduled as follows based on the book value as of December 31, 2020.


2021	$	502.5
2022	250.2
2023	498.9
2024	498.3
2025	0.0
Thereafter	1,668.4
Total long-term debt	$	3,418.3

Our 3.75% Senior Notes in aggregate principal amount of $500.0 mature on October 1, 2021. We expect to use available cash on hand as well as additional short-term borrowings as needed to fund the principal repayment. For those debt securities that have a premium or discount at the time of issuance, we amortize the amount through interest expense based on the maturity date or the first date the holders may require us to repurchase the debt securities, if applicable. A premium would result in a decrease in interest expense, and a discount would result in an increase in interest expense in future periods. Additionally, we have debt issuance costs related to certain financing transactions which are also amortized through interest expense. As of December 31, 2020 and 2019, we had total unamortized debt issuance costs of $24.3 and $21.6, respectively. Our debt securities include covenants that, among other things, limit our liens and the liens of certain of our consolidated subsidiaries, but do not require us to maintain any financial ratios or specified levels of net worth or liquidity.

As of December 31, 2020 and December 31, 2019, the estimated fair value of the Company's long-term debt was $3,995.0 and $3,565.5, respectively. Refer to Note 13 for details.

Debt Transactions

3.50% Senior Notes Due 2020

Our 3.50% Senior Notes in aggregate principal amount of $500.0 matured on October 1, 2020, and we used available cash, including the proceeds from the offering of our 4.75% Senior Notes, to fund the principal repayment.

4.75% Senior Notes Due 2030

On March 30, 2020, we issued a total of $650.0 in aggregate principal amount of 4.75% senior unsecured notes (the “4.75% Senior Notes”) due March 30, 2030. Upon issuance, the 4.75% Senior Notes were reflected at $640.0, net of discount of $3.8 and net of capitalized debt issuance costs, including commissions and offering expenses of $6.2, both of which will be amortized in interest expense through the maturity date using the effective method. Interest is payable semi-annually in arrears on March 30th and September 30th of each year, commencing on September 30, 2020.

We may redeem the 4.75% Senior Notes at any time in whole, or from time to time in part, in accordance with the provisions of the indenture, including the supplemental indenture, under which the 4.75% Senior Notes were issued. Additionally, upon the occurrence of a change of control repurchase event with respect to the 4.75% Senior Notes, each holder of the 4.75% Senior Notes has the right to require the Company to purchase that holder’s 4.75% Senior Notes at a price equal to 101% of the principal amount thereof, plus accrued and unpaid interest, unless the Company has exercised its option to redeem all the 4.75% Senior Notes.

Credit Arrangements

Credit Agreement

We maintain a committed corporate credit facility, originally dated as of July 18, 2008, which has been amended and restated from time to time (the "Credit Agreement"). We use our Credit Agreement to increase our financial flexibility, to provide letters of credit primarily to support obligations of our subsidiaries and to support our commercial paper program. The Credit Agreement is a revolving facility, expiring in November 2024, under which amounts borrowed by us or any of our subsidiaries designated under the Credit Agreement may be repaid and reborrowed, subject to an aggregate lending limit of $1,500.0, or the equivalent in other currencies. The Company has the ability to increase the commitments under the Credit Agreement from time to time by an additional amount of up to $250.0, provided the Company receives commitments for such increases and satisfies certain other conditions. The aggregate available amount of letters of credit outstanding may decrease or increase, subject to a sublimit on letters of credit of $50.0, or the equivalent in other currencies. Our obligations under the Credit Agreement are unsecured. As of December 31, 2020 and 2019, there were no borrowings under the Credit Agreement; however, we had $9.0 and $8.4 of letters of credit under the Credit Agreement, which reduced our total availability to $1,491.0 and $1,491.6, respectively. In addition to other and customary covenants, we are required to maintain the financial covenant listed below as of the end of each fiscal quarter for the period of four fiscal quarters then ended pursuant to our Credit Agreement. We were in compliance with all of our covenants in the Credit Agreement as of December 31, 2020.

Under the Credit Agreement, we can elect to receive advances bearing interest based on either the Base Rate or the Eurocurrency rate (each as defined in the Credit Agreement) plus an applicable margin that is determined based on our credit ratings. As of December 31, 2020, the applicable margin was 0.125% for Base Rate advances and 1.125% for Eurocurrency Rate borrowings. Letter of credit fees accrue on the average daily aggregate amount of letters of credit outstanding, at a rate equal to the applicable margin for Eurocurrency rate advances, and fronting fees accrue on the aggregate amount of letters of credit outstanding at an annual rate of 0.250%. We also pay a facility fee on each lender's revolving commitment of 0.125%, which is an annual rate determined based on our credit ratings.

364-Day Credit Facility

On March 27, 2020, we entered into an agreement for a 364-day revolving credit facility (the "364-Day Credit Facility") that matures on March 26, 2021. The 364-Day Credit Facility is a revolving facility, under which amounts borrowed by us may be repaid and reborrowed, subject to an aggregate lending limit of $500.0. The cost structure of the 364-Day Credit Agreement is based on the Company’s current credit ratings. The applicable margin for Base Rate Advances (as defined in the 364-Day Credit Facility) is 0.250%, the applicable margin for Eurodollar Rate Advances (as defined in the 364-Day Credit Facility) is 1.250%, and the facility fee payable on a lender’s revolving commitment is 0.250%. In addition, the 364-Day Credit Facility includes covenants that, among other things, (i) limit our liens and the liens of our consolidated subsidiaries, and (ii) limit subsidiary debt. The 364-Day Credit Facility also contains a financial covenant that requires us to maintain, on a consolidated basis as of the end of each fiscal quarter, a leverage ratio for the four quarters then ended. The leverage ratio and other covenants set forth in the 364-Day Credit Facility are equivalent to the covenants contained in the Company’s existing Credit Agreement, which remains in full effect. As of December 31, 2020, there were no borrowings under the 364-Day Credit Facility, and we were in compliance with all of our covenants in the 364-Day Credit Facility.

The Amendments

On July 28, 2020, we entered into Amendment No. 1 to the Credit Agreement and Amendment No. 1 to the 364-Day Credit Facility (together, the “Amendments”). The Amendments increased the maximum leverage ratio covenant to 4.25x in the case of the 364-Day Credit Facility and, in the case of the Credit Agreement, to (i) 4.25x through the quarter ended June 30, 2021, and (ii) 3.50x thereafter. Amendment No.1 to the Credit Agreement also increased the Applicable Margin (as defined in the Credit Agreement) for any borrowings we make under the Credit Agreement if our long-term public debt ratings are BB+/Ba1 or below at the time of borrowing. We have the option to terminate Amendment No.1 to the Credit Agreement at any time, provided that at the time we deliver a termination notice, the leverage ratio as of the end of the most recently ended fiscal quarter did not exceed 3.50x. The Credit Agreement reverts to its original terms on June 30, 2021, or following any such early termination, whichever is earlier. We paid amendment fees of $2.0 in connection with the Amendments.

In addition to other and customary covenants, we are required to maintain the financial covenant listed below as of the end of each fiscal quarter for the period of four fiscal quarters then ended pursuant to our Credit Agreement and 364-Day Credit Facility.


						Financial Covenant
Leverage ratio (not greater than): 1, 2						4.25x

1The leverage ratio is defined as debt as of the last day of such fiscal quarter to EBITDA, as defined in the Credit Agreement, for the four quarters then ended.

2On July 28, 2020, the Amendments increased the maximum leverage ratio covenant from 3.75x to 4.25x in the case of the 364-Day Credit Facility and, in the case of the Credit Agreement, to (i) 4.25x through the quarter ended June 30, 2021, and (ii) 3.50x thereafter.

Uncommitted Lines of Credit

We also have uncommitted lines of credit with various banks that permit borrowings at variable interest rates and that are primarily used to fund working capital needs. We have guaranteed the repayment of some of these borrowings made by certain subsidiaries. If we lose access to these credit lines, we would have to provide funding directly to some of our operations. As of December 31, 2020 and 2019, the Company had uncommitted lines of credit in an aggregate amount of $857.6 and $1,056.0, under which we had outstanding borrowings of $48.0 and $52.4 classified as short-term borrowings on our Consolidated Balance Sheets, respectively. The average amounts outstanding during 2020 and 2019 were $86.5 and $88.0, respectively, with weighted-average interest rates of approximately 3.6% and 5.2%, respectively.

Commercial Paper

The Company is authorized to issue unsecured commercial paper up to a maximum aggregate amount outstanding at any time of $1,500.0. Borrowings under the commercial paper program are supported by the Credit Agreement described above. Commercial paper proceeds are used for working capital and general corporate purposes, including the repayment of maturing indebtedness and other short-term liquidity needs. Commercial paper maturities vary but may not exceed 397 days from the date of issue. As of December 31, 2020 and 2019, there was no commercial paper outstanding. The average amounts outstanding under the program in 2020 and 2019 were $105.8 and $312.9 with weighted-average interest rates of approximately 1.5% and 2.5% and weighted-average maturities of twelve and thirteen days, respectively.

Cash Pooling

We aggregate our domestic cash position on a daily basis. Outside the United States, we use cash pooling arrangements with banks to help manage our liquidity requirements. In these pooling arrangements, several IPG agencies agree with a single bank that the cash balances of any of the agencies with the bank will be subject to a full right of set-off against amounts other agencies owe the bank, and the bank provides for overdrafts as long as the net balance for all agencies does not exceed an agreed-upon level. Typically, each agency pays interest on outstanding overdrafts and receives interest on cash balances. Our Consolidated Balance Sheets reflect cash, net of bank overdrafts, under all of our pooling arrangements, and as of December 31, 2020 and 2019 the amounts netted were $2,702.2 and $2,274.9, respectively.

Earnings Per Share (Notes)

12 Months Ended

Dec. 31, 2020

Earnings Per Share [Abstract]

Earnings Per Share

The following sets forth basic and diluted earnings per common share available to IPG common stockholders.


	Years ended December 31,
	2020		2019		2018
Net income available to IPG common stockholders	$	351.1	$	656.0	$	618.9

Weighted-average number of common shares outstanding - basic	389.4		386.1		383.3
Dilutive effect of stock options and restricted shares	3.8		5.1		5.7
Weighted-average number of common shares outstanding - diluted	393.2		391.2		389.0

Earnings per share available to IPG common stockholders:
Basic	$	0.90	$	1.70	$	1.61
Diluted	$	0.89	$	1.68	$	1.59

Acquisitions (Notes)

12 Months Ended

Dec. 31, 2020

Business Combinations [Abstract]

Business Combination Disclosure [Text Block]

Acquisitions

Acxiom Acquisition

On October 1, 2018, pursuant to the terms of the Membership Interest Purchase Agreement dated as of July 2, 2018, the Company completed the acquisition of Acxiom Holdings, Inc.’s Marketing Solutions business ("Acxiom") through the acquisition of 100% of the equity interests of Acxiom for $2,327.9, subject to customary closing adjustments. The purpose of the acquisition is to combine the Company's media, creative, marketing services and analytics capabilities, global scale and consumer insights, with Acxiom's expertise in identity, data, integrations and data stewardship.

The Company funded the acquisition of Acxiom from a term loan agreement with third-party lenders for $500.0 and unsecured senior notes issued for a total of $2,000.0 in aggregate principal amount.

The following table summarizes the fair values of the assets acquired and liabilities assumed at the closing date:


	October 1, 2018
Cash and cash equivalents	$	13.3
Accounts receivable	112.9
Accounts receivable, billable to clients	8.3
Other current assets	28.2
Property and equipment, net	159.7
Deferred income taxes	(0.6)
Goodwill	1,110.8
Intangible assets, net	995.0
Other non-current assets	8.3
Accounts payable	(37.1)
Accrued liabilities	(46.9)
Contract liabilities	(23.2)
Other non-current liabilities	(0.8)
Net assets acquired	$	2,327.9

The fair values of the identifiable intangible assets acquired at the closing date are as follows:


	Fair Value		Weighted Average Amortization Period (Years)
Customer lists	$	600.0	15.0
Know-how and technology	235.0		9.0
Trade names	160.0		15.0 to indefinite
Total intangible assets	$	995.0

The fair value of the customer lists was determined by applying the multi-period excess earnings method, a variation of the income approach. The fair values of the know-how and technology and the trade names were determined using the relief from royalty method of the income approach. Goodwill generated by the Acxiom acquisition, the majority of which is tax deductible, primarily relates to intangible assets that do not qualify for separate recognition, including assembled workforce and synergies. The purchase accounting for the transaction was finalized during the third quarter of 2019, including the assignment of goodwill related to the transaction-associated synergies. There were no material adjustments to the preliminary amounts recorded.

The operating results of Acxiom for the period from October 1, 2018 to December 31, 2018, including net revenue of $181.7 and net income available to IPG common stockholders of $20.4, are included in our Consolidated Statements of Operations for the year ended December 31, 2018.

The Company incurred a total of $35.0 in "Selling, general and administrative expenses," $3.7 in "Interest expense," $0.4 in "Interest income" and $10.3 in "Other expense, net," for transaction-related costs in connection with the acquisition.

The following table presents the combined results of the Company and Acxiom for the year ended December 31, 2018 on an unaudited pro forma basis, as if the acquisition had occurred on January 1, 2017. The unaudited pro forma financial information is presented for informational purposes only and is not indicative of the results of operations that would have been achieved if that acquisition had taken place at the beginning of January 1, 2017. It also does not reflect changes in cost structure or operations resulting from restructuring activities, changes in the business, or future events that may occur after the completion of the acquisition. The pro forma combined results of operations shown below include the business combination accounting effects resulting from the acquisition.


	(Unaudited)
	December 31,
	2018
Pro forma revenues	$	10,230.4
Pro forma net income	642.2

Other Acquisitions

We continue to evaluate strategic opportunities to expand our industry expertise, strengthen our position in high-growth and key strategic geographical markets and industry sectors, advance technological capabilities and improve operational efficiency through both acquisitions and increased ownership interests in current investments. Our acquisitions typically provide for an initial payment at the time of closing and additional contingent purchase price payments based on the future performance of the acquired entity. We have entered into agreements that may require us to purchase additional equity interests in certain consolidated and unconsolidated subsidiaries. The amounts at which we record these transactions in our financial statements are based on estimates of the future financial performance of the acquired entity, the timing of the exercise of these rights, changes in foreign currency exchange rates and other factors.

During 2020 we completed four acquisitions, three of which were included in the IAN reportable segment, and one of which were included in the DXTRA reportable segment. These acquisitions include traditional advertising agency based in Colombia, a marketing and communications agency based in the U.K., a boutique post-production company based in New York, and a mobile app design agency based in the U.K. During 2020, we recorded approximately $28.0 of goodwill and other intangible assets related to our acquisitions.

During 2019, we completed one acquisition, a content communications agency based in the U.K. This acquisition was included in the IAN reportable segment. During 2019, we recorded approximately $7.6 of goodwill and other intangible assets related to our acquisitions.

During 2018, we completed five acquisitions, two of which were included in the IAN reportable segment, and three of which were included in the DXTRA reportable segment. These acquisitions include a data and technology company based in the U.S., as discussed in detail above, a full-service digital agency based in Brazil, an entertainment marketing and brand

licensing agency in the fashion and lifestyle sector based in the U.K., a content-focused social creative agency based in the U.K. and a content production firm based in Israel. During 2018, we recorded approximately $2,131.0 of goodwill and other intangible assets related to our acquisitions.

The results of operations of our acquired companies were included in our consolidated results from the closing date of each acquisition. We did not make any payments in stock related to our acquisitions in 2020, 2019 or 2018.

Details of cash paid for current and prior years' acquisitions are listed below.


	Years ended December 31,
	2020		2019		2018
Cost of investment: current-year acquisitions 1	$	8.5	$	0.6	$	2,323.4
Cost of investment: prior-year acquisitions	45.9		15.8		33.9
Less: net cash acquired	(2.9)		—		(13.8)
Total cost of investment	51.5		16.4		2,343.5
Operating payments 2	2.9		9.3		19.4
Total cash paid for acquisitions 3	$	54.4	$	25.7	$	2,362.9

1The cost of investment: current-year acquisitions line significantly increased in the year ended December 31, 2018, primarily as a result of payments related to the acquisition of Acxiom.

2Represents cash payments for amounts that have been recognized in operating expenses since the date of acquisition either relating to adjustments to estimates in excess of the initial value of contingent payments recorded or were contingent upon the future employment of the former owners of the acquired companies. Amounts are reflected in the operating section of the Consolidated Statements of Cash Flows.

3Of the total cash paid for acquisitions, $4.9, $0.6 and $2,309.8 for the years ended December 31, 2020, 2019 and 2018, respectively, are classified under the investing section of the Consolidated Statements of Cash Flows as acquisitions, net of cash acquired. These amounts relate to initial payments for new transactions. Of the total cash paid for acquisitions, $46.6, $15.8 and $33.7 for the years ended December 31, 2020, 2019 and 2018, respectively, are classified under the financing section of the Consolidated Statements of Cash Flows as acquisition-related payments. These amounts relate to deferred payments and increases in our ownership interest for prior acquisitions.

For companies acquired, we estimate the fair values of the assets and liabilities based on 100% of the business for consolidation. The purchase price in excess of the estimated fair value of the tangible net assets acquired is allocated to identifiable intangible assets and then to goodwill. Due to the characteristics of advertising, specialized marketing and communication services companies, our acquisitions typically do not have significant amounts of tangible assets since the principal assets we acquire are client relationships and talent. As a result, a substantial portion of the purchase price is primarily allocated to customer lists, trade names and goodwill.

For acquisitions we record deferred payment and redeemable noncontrolling interest amounts on our Consolidated Balance Sheets based on their acquisition-date fair value. Deferred payments are recorded on a discounted basis and adjusted quarterly, if necessary, through operating income or net interest expense, depending on the nature of the arrangement, for both changes in estimate and accretion between the acquisition date and the final payment date. See Note 16 for further information on contingent acquisition obligations. Redeemable noncontrolling interests are adjusted quarterly, if necessary, to their estimated redemption value, but not less than their initial fair value. Any adjustments to the redemption value impact retained earnings or additional paid in capital, except for foreign currency translation adjustments. The following table presents changes in our redeemable noncontrolling interests.


	Years ended December 31,
	2020		2019		2018
Balance at beginning of period	$	164.7	$	167.9	$	252.1
Change in related noncontrolling interests balance	(5.4)		(2.8)		(10.7)
Changes in redemption value of redeemable noncontrolling interests:
Additions	0.0		24.3		0.0
Redemptions and other	(20.6)		(24.9)		(33.7)
Redemption value adjustments 1	(45.6)		0.2		(39.8)
Balance at end of period	$	93.1	$	164.7	$	167.9

1Redemption value adjustments for the year ended December 31, 2020 were primarily attributable to the expiration of redemption provisions related to redeemable noncontrolling interests.

For all acquisitions, if a portion of the deferred payments and purchases of additional interests after the effective date of purchase are contingent upon employment terms, then that amount is accounted for separately from the business combination and recognized as compensation expense over the required earn-out period. Payments deemed as compensation are excluded from the fair value purchase price allocation to tangible net assets and intangible assets acquired.

Supplementary Data (Notes)

12 Months Ended

Dec. 31, 2020

Dec. 31, 2019

Supplementary Data [Abstract]

Supplementary Data

Valuation and Qualifying Accounts – Accounts Receivable, Allowance for Expected Credit Losses


	Years ended December 31,
	2020		2019		2018
Balance at beginning of period	$	40.2	$	42.5	$	42.7
Cumulative effect of accounting change 1	9.0		N/A		N/A
Charges to costs and expenses	50.5		10.1		6.5
Adjustments:
Acquisitions/(dispositions)	8.6		(0.3)		2.2
Uncollectible accounts written off	(11.2)		(11.9)		(7.1)
Recoveries	0.2		N/A		N/A
Foreign currency translation adjustments	1.0		(0.2)		(1.8)
Balance at end of period	$	98.3	$	40.2	$	42.5

Property and Equipment


	December 31,
	2020		2019
Furniture and equipment	$	654.6	$	694.3
Leasehold improvements	554.6		634.9
Internal-use computer software	470.1		422.0
Land and buildings	144.9		143.3
Gross property and equipment	1,824.2		1,894.5
Less: accumulated depreciation and amortization	(1,133.9)		(1,116.4)
Total property and equipment, net	$	690.3	$	778.1

Total depreciation and amortization expense, which excludes the amortization of acquired intangibles, for property and equipment for the years ended December 31, 2020, 2019 and 2018 was $204.7, $192.5 and $165.3, respectively.

Accrued Liabilities

The following table presents the components of accrued liabilities.


	December 31,
	2020		2019
Salaries, benefits and related expenses	$	504.6	$	494.1
Restructuring charges	69.5		1.6
Income taxes payable	50.6		43.2
Acquisition obligations	47.9		45.7
Interest	43.6		38.8
Office and related expenses	25.5		26.9
Other	90.7		92.5
Total accrued liabilities	$	832.4	$	742.8

Other Expense, Net

Results of operations include certain items that are not directly associated with our revenue-producing operations.


	Years ended December 31,
	2020		2019		2018
Net losses on sales of businesses	$	(67.0)	$	(43.4)	$	(61.9)
Other	2.6		0.5		(7.7)
Total other expense, net	$	(64.4)	$	(42.9)	$	(69.6)

Net losses on sales of businesses – During 2020 and 2019, the amounts recognized were related to sales of businesses and the classification of certain assets and liabilities, consisting primarily of cash, as held for sale within our IAN and DXTRA reportable segments. During 2018, the amounts recognized were related to sales of businesses and the classification of certain assets and liabilities, consisting primarily of cash, as held for sale within our IAN and DXTRA reportable segments. The businesses held for sale as of year-end primarily represent unprofitable, non-strategic agencies which are expected to be sold within the next twelve months. The sales of businesses and the classification of certain assets and liabilities as held for sale included cash, net of proceeds, of $62.9, $6.7 and $30.8 for the years ended 2020, 2019 and 2018, respectively, which is classified within the Other Investing Activities line in our Consolidated Statements of Cash Flows.

Other – During 2020, the amounts recognized were primarily a result of gains on remeasurement of equity interest arising from a change in ownership. During 2019, the amounts recognized are primarily a result of changes in fair market value of equity investments, partially offset by the sale of an equity investment. During 2018, the amounts recognized are primarily a result of transaction-related costs from the Acxiom acquisition, partially offset by changes in fair market value of equity investments.

Share Repurchase Program

On July 2, 2018, in connection with the announcement of the Acxiom acquisition, we announced that share repurchases will be suspended for a period of time in order to reduce the increased debt levels incurred in conjunction with the acquisition. As of December 31, 2020, $338.4, excluding fees, remains available for repurchase under the share repurchase programs authorized in previous years, which has no expiration date.

Supplementary Data

Cash Flow, Supplemental Disclosures

Supplemental Cash Flow Information


	Years ended December 31,
	2020		2019		2018
Cash paid for interest	$	182.2	$	192.7	$	88.7
Changes in operating lease right-of-use assets and lease liabilities 1	192.6		9.4		N/A
Cash paid for income taxes, net of refunds 2	89.1		150.2		207.9

1For the year ended December 31, 2020, comprised of the impairments of operating lease right-of-use asset of $209.9, classified in Non-cash restructuring charges, partially offset by $17.3 net cash outflow, classified in Other non-current assets and liabilities in our Consolidated Statements of Cash Flows. For the year ended December 31, 2019, comprised of the impairments of operating lease right-of-use assets of $8.7, classified in Non-cash restructuring charges and $0.7, classified in Other non-current assets and liabilities in our Consolidated Statements of Cash Flows.

2Refunds of $124.2, $92.6 and $24.3 were received for the years ended December 31, 2020, 2019 and 2018, respectively.

Goodwill and Other Intangible Assets (Notes)

12 Months Ended

Dec. 31, 2020

Goodwill and intangible assets [Abstract]

Goodwill and Intangible Assets Disclosure [Text Block]

Goodwill and Other Intangible Assets

Goodwill

Goodwill is the excess purchase price remaining from an acquisition after an allocation of purchase price has been made to identifiable assets acquired and liabilities assumed based on estimated fair values. The changes in the carrying value of goodwill for our reportable segments, IAN and DXTRA, for the years ended December 31, 2020 and 2019 are listed below.


	IAN		DXTRA		Total 1
Balance as of December 31, 2018	$	4,201.5	$	674.4	$	4,875.9
Acquisitions	2.1		0.7		2.8
Foreign currency and other	14.5		1.2		15.7
Balance as of December 31, 2019	$	4,218.1	$	676.3	$	4,894.4
Acquisitions	23.5		0.5		24.0
Foreign currency and other	22.9		4.2		27.1
Balance as of December 31, 2020	$	4,264.5	$	681.0	$	4,945.5

1For all periods presented, no goodwill impairment charge has been recorded.

See Note 1 for information regarding our annual impairment testing methodology.

Other Intangible Assets

Other intangible assets primarily consist of customer lists and know-how and technology, which have definite lives and are subject to amortization on a straight-line basis with estimated useful lives generally between 7 and 15 years, as well as trade names which have both indefinite and definite lives which are subject to amortization on a straight-line basis with estimated useful lives of 15 years. Amortization expense for other intangible assets for the years ended December 31, 2020, 2019 and 2018 was $85.9, $86.0 and $37.6, respectively. There were no material impairment charges on other intangibles for the years ended December 31, 2020, 2019 and 2018. During 2020 and 2019, we recorded approximately $4.0 and $5.0 of other intangible assets related to our acquisitions in the respective year.

The following table provides a summary of other intangible assets, which are included in our Consolidated Balance Sheets.


	December 31,
	2020						2019
	Gross Amount		Accumulated Amortization		Net Amount		Gross Amount		Accumulated Amortization		Net Amount
Customer lists	$	859.5	$	(293.3)	$	566.2	$	861.4	$	(244.6)	$	616.8
Know-how and technology	235.4		(58.9)		176.5		235.0		(32.9)		202.1
Trade names	224.4		(44.1)		180.3		226.2		(41.3)		184.9
Other	14.6		(4.0)		10.6		14.3		(3.8)		10.5
Total	$	1,333.9	$	(400.3)	$	933.6	$	1,336.9	$	(322.6)	$	1,014.3

The estimated annual amortization expense for other intangible assets for the next five years as of December 31, 2020 is listed below.


	2021		2022		2023		2024		2025
Estimated amortization expense	$	88.3	$	83.8	$	79.0	$	77.3	$	74.5

Income Taxes (Notes)	12 Months Ended
Income Taxes (Notes)	Dec. 31, 2020
Income Tax Disclosure [Abstract]
Income Tax Disclosure [Text Block]	As of December 31, 2020, there were $1,188.8 of loss carryforwards. These loss carryforwards were all non-U.S. tax loss carryforwards, of which $1,035.3 have unlimited carryforward periods and $153.5 have expiration periods from 2021 to 2041. As of December 31, 2020, the Company also had $31.4 in deferred tax assets for state net operating loss carryforwards and tax credit carryforwards, which will expire between 2021 and 2041. As of December 31, 2020 and 2019, we had $1,080.2 and $1,199.7, respectively, of undistributed earnings attributable to foreign subsidiaries. The Company has historically asserted that its unremitted foreign earnings are permanently reinvested, and therefore has not recorded any deferred taxes on such amounts. It is not practicable to determine the deferred tax on these undistributed earnings because such liability, if any, is dependent on circumstances that exist if and when a remittance occurs, including the source location and amount of the distribution and foreign withholding taxes. In the second quarter of 2020, in response to changes in non-US tax law, a decision was made to change our indefinite reinvestment assertion on a $120.0 of undistributed foreign earnings of specific subsidiaries. We recorded $10.4 of income tax costs associated with this change to our assertion. In the third quarter of 2020, in response to restructuring actions taken within foreign subsidiaries, a decision was made to change our indefinite reinvestment assertion on a $46.0 of undistributed foreign earnings of specific subsidiaries. We recorded $3.2 of income tax costs associated with this change to our assertion. During the third quarter ended September 30, 2018, as a result of our increased debt and associated servicing commitments in connection with the Acxiom acquisition that was consummated on October 1, 2018, the Company re-evaluated its global cash needs and as a result determined that approximately $435.0 of undistributed foreign earnings from certain international entities were no longer subject to the permanent reinvestment assertion. We recorded a tax expense of $10.8 in 2018 representing our estimate of the tax costs associated with this change to our assertion. We have not changed our permanent reinvestment assertion with respect to any other international entities as we intend to use the related historical earnings and profits to fund international operations and investments.

- Definition

The entire disclosure for income taxes. Disclosures may include net deferred tax liability or asset recognized in an enterprise's statement of financial position, net change during the year in the total valuation allowance, approximate tax effect of each type of temporary difference and carryforward that gives rise to a significant portion of deferred tax liabilities and deferred tax assets, utilization of a tax carryback, and tax uncertainties information.

+ References + Details

Accumulated Other Comprehensive Loss, Net of Tax (Notes)

12 Months Ended

Dec. 31, 2020

Accumulated Other Comprehensive Loss [Abstract]

Comprehensive Income (Loss) Note

Accumulated Other Comprehensive Loss, Net of Tax

The following table presents the changes in accumulated other comprehensive loss, net of tax, by component.


	Foreign Currency Translation Adjustments		Derivative Instruments		Defined Benefit Pension and Other Postretirement Plans		Total
Balance as of December 31, 2018	$	(716.4)	$	(5.3)	$	(219.4)	$	(941.1)
Other comprehensive income (loss) before reclassifications	12.0		0.0		(14.7)		(2.7)
Amount reclassified from accumulated other comprehensive loss, net of tax	6.7		1.8		5.3		13.8
Balance as of December 31, 2019	$	(697.7)	$	(3.5)	$	(228.8)	$	(930.0)
Other comprehensive income (loss) before reclassifications	40.1		8.5		(26.3)		22.3
Amount reclassified from accumulated other comprehensive loss, net of tax	20.0		1.8		5.7		27.5
Balance as of December 31, 2020	$	(637.6)	$	6.8	$	(249.4)	$	(880.2)

Amounts reclassified from accumulated other comprehensive loss, net of tax, for the years ended December 31, 2020, 2019 and 2018 are as follows:


	Years ended December 31,						Affected Line Item in the Consolidated Statements of Operations
	2020		2019		2018
Foreign currency translation adjustments 1	$	20.0	$	6.7	$	15.7	Other expense, net
Losses on derivative instruments	2.4		2.3		2.2		Interest expense
Amortization of defined benefit pension and postretirement plans items	7.3		6.7		6.5		Other expense, net
Tax effect	(2.2)		(1.9)		(2.3)		Provision for income taxes
Total amount reclassified from accumulated other comprehensive loss, net of tax	$	27.5	$	13.8	$	22.1

1These foreign currency translation adjustments are primarily a result of the sales of businesses.

Restructuring Charges (Notes)

12 Months Ended

Dec. 31, 2020

Restructuring Charges [Abstract]

Restructuring and Related Activities Disclosure [Text Block]

Restructuring Charges


	Years ended December 31,
	2020		2019		2018
Severance and termination costs	$	140.4	$	22.0	$	0.0
Lease restructuring costs	256.0		11.9		0.0
Other restructuring costs	17.4		0.0		0.0
Total restructuring charges	$	413.8	$	33.9	$	0.0

2020 Restructuring Plan

Beginning in the second quarter of 2020, the Company took restructuring actions to lower its operating expenses structurally and permanently relative to revenue and to accelerate the transformation of our business (the “2020 Plan”). These actions continued through the fourth quarter and most are based on our recent experience and learning in the COVID-19 pandemic and a resulting review of our operations to address certain operating expenses such as occupancy expense and salaries and related expenses.

A summary of the restructuring activities related to the 2020 Plan is as follows:


	2020 Plan
	Restructuring Expense		Non-Cash Items		Cash Payments		Liability at December 31, 2020
Severance and termination costs	$	140.4	$	4.5	$	61.3	$	74.6
Lease impairment costs	256.0		256.0		0.0		0.0
Other	17.4		5.1		12.3		0.0
Total	$	413.8	$	265.6	$	73.6	$	74.6

Our charges for restructuring actions for the year ended December 31, 2020 totaled $413.8 and were designed to reduce our expenses, such as occupancy expense and salaries and related expenses, relative to our net revenue on an ongoing basis. These actions, taken during the second, third and fourth quarters, reduced our global real estate footprint by approximately 15% or 1,700,000 square feet and, further, downsized selected levels of management and staff with severance costs for 1,520 employees or approximately 3%. Of the total charges for the year ended December 31, 2020, $265.6 or 64%, is non-cash, mainly representing the impairment of right-of-use assets of operating leases.

Net restructuring charges were comprised of $317.9 at IAN and $78.8 at DXTRA for the year ended December 31, 2020, which include non-cash lease impairment costs of $190.4 and $59.8, respectively.

Lease impairment costs, which relate to the office spaces that were vacated as part of the 2020 Plan, included impairments of operating lease right-of-use assets and associated leasehold improvements, furniture and asset retirement obligations. Lease impairments were calculated based on estimated fair values using market participant assumptions including forecasted net discounted cash flows related to the operating lease right-of-use assets.

2019 Restructuring Plan

In the first quarter of 2019, the Company implemented a cost initiative (the “2019 Plan”) to better align our cost structure with our revenue primarily related to specific client losses occurring in 2018. All restructuring actions were identified and initiated by the end of the first quarter of 2019, with all actions substantially completed by the end of the second quarter of 2019, and there have not been any restructuring adjustments.

Incentive Compensation Plans (Notes)

12 Months Ended

Dec. 31, 2020

Share-based Payment Arrangement, Additional Disclosure [Abstract]

Incentive Compensation Plans

2019 & 2014 Performance Incentive Plan

We issue stock-based compensation and cash awards to our employees under various plans established by the Compensation and Leadership Talent Committee of the Board of Directors (the “Compensation Committee”) and approved by our shareholders. In May 2019, our shareholders approved the 2019 Performance Incentive Plan (the “2019 PIP”), replacing the

2014 Performance Incentive Plan (the “2014 PIP”) and previous incentive plans. The number of shares of common stock initially available for grants of all equity awards under the 2019 PIP is 27.0. Pursuant to the terms of the 2019 PIP, the number of shares that may be awarded to any one participant for any stock based awards is limited to 2.0. The vesting period of awards granted is generally commensurate with the requisite service period. We generally issue new shares to satisfy the exercise of stock options or the distribution of other stock-based awards.

Additionally, under the 2019 PIP, we have the ability to issue performance cash awards. The performance cash awards are granted to certain employees who otherwise would have been eligible to receive performance-based stock awards. These awards have a service period vesting condition and a performance vesting condition. The amount of the performance cash award received by an employee with a performance vesting condition can range from 0% to 300% of the target amount of the original grant value, except for Executive Officers of IPG, with a range of 0% to 200%. Performance cash awards generally vest in three years. The Compensation Committee may grant performance cash awards to any eligible employee; however, no employee can receive more than $10.0 during a performance period.

The amounts of stock-based compensation expense as reflected in salaries and related expenses in our Consolidated Statements of Operations, and the related tax benefit, are listed below.


	Years ended December 31,
	2020		2019		2018
Stock-settled awards	$	38.4	$	33.5	$	24.7
Cash-settled awards	1.0		0.8		0.6
Performance-based awards	28.6		46.7		57.5
Employee stock purchase plan	1.4		1.1		0.9
Other 1	1.7		0.6		0.9
Stock-based compensation expense	$	71.1	$	82.7	$	84.6
Tax benefit	$	17.3	$	20.0	$	20.4

1Represents charges recorded for severance expense related to stock-based compensation awards.

Stock Options

Stock options are granted with the exercise price equal to the fair market value of our common stock on the grant date. We use the Black-Scholes option-pricing model to estimate the fair value of options granted, which requires the input of subjective assumptions including the option’s expected term and the price volatility of the underlying stock. They are generally first exercisable between two and four years from the grant date and expire ten years after the grant date (or earlier in the case of certain terminations of employment). There were no stock options granted during the years ended December 31, 2020, 2019 and 2018. As of December 31, 2020, all stock options granted were fully vested and exercisable.

The following table summarizes our stock option activity during 2020.


	Options	Weighted- Average Exercise Price (per option)		Weighted- Average Remaining Contractual Term (in years)	Aggregate Intrinsic Value
Stock options outstanding as of January 1, 2020	1.2	$	12.26
Exercised	(0.6)	$	11.70
Stock options outstanding as of December 31, 2020	0.6	$	12.75	2.2	$	6.8

There were 0.6, 0.6 and 1.9 stock options exercised in 2020, 2019 and 2018, respectively. The total intrinsic value of stock options exercised during 2020, 2019 and 2018 was $5.3, $9.1 and $27.9, respectively. The cash received from the stock options exercised in 2020, 2019 and 2018 was $9.1, $8.3 and $29.0, which included taxes withheld of $2.6, $4.0, and $13.3, respectively.

Stock-Based Compensation

We grant other stock-based compensation awards such as stock-settled awards, cash-settled awards and performance-based awards (settled in cash or shares) to certain key employees. The number of shares or units received by an employee for performance-based awards depends on Company performance against specific performance targets and could range from 0% to 300% of the target amount of shares originally granted, except for Executive Officers of IPG, with a range of 0% to 200%. Incentive awards are subject to certain restrictions and vesting requirements as determined by the Compensation Committee.

The fair value of the shares on the grant date is amortized over the vesting period, which is generally three years. Upon completion of the vesting period for cash-settled awards, the grantee is entitled to receive a payment in cash based on the fair market value of the corresponding number of shares of common stock. No monetary consideration is paid by a recipient for any incentive award. The fair value of cash-settled awards is adjusted each quarter based on our share price. The holders of certain stock-settled awards have the right to receive dividends. Dividends declared on common stock are accrued during the vesting period and paid when the award vests. The holders of performance-based awards have no ownership interest in the underlying shares of common stock until the awards vest and the shares of common stock are issued.

Stock-based compensation awards expected to be settled in cash have been classified as liabilities in our Consolidated Balance Sheets as of December 31, 2020 and 2019.


	Years ended December 31,
	2020		2019		2018
Stock-Settled Awards:
Awards granted	2.3		2.5		2.1
Weighted-average grant-date fair value (per award)	$	20.70	$	22.78	$	23.60
Total fair value of vested awards distributed	$	17.3	$	15.2	$	24.2
Cash-Settled Awards:
Awards granted	0.0		0.0		0.1
Weighted-average grant-date fair value (per award)	$	21.02	$	22.83	$	23.62
Total fair value of vested awards distributed	$	0.3	$	0.9	$	0.8
Performance-Based Awards:
Awards granted	2.4		2.1		2.9
Weighted-average grant-date fair value (per award)	$	18.67	$	20.16	$	21.13
Total fair value of vested awards distributed	$	53.3	$	64.9	$	87.2

In conjunction with common stock dividends declared in 2020 and 2019, we accrued dividends of $5.6 and $4.2, respectively, on non-vested stock-settled and cash-settled awards and paid dividends of $1.5 and $1.2 for stock-settled and cash-settled awards that vested during 2020 and 2019, respectively.

A summary of the activity of our non-vested stock-settled awards, cash-settled awards and performance-based awards during 2020 is presented below (performance-based awards are shown at 100% of the shares originally granted).


	Stock-Settled Awards				Cash-Settled Awards				Performance-Based Awards
	Awards		Weighted- Average Grant-Date Fair Value (per award)		Awards		Weighted- Average Grant-Date Fair Value (per award)		Awards		Weighted- Average Grant-Date Fair Value (per award)
Non-vested as of January 1, 2020	4.7		$	23.21	0.1		$	23.20	5.6		$	21.36
Granted	2.3		20.70		0.0		21.02		2.4		18.67
Vested	(0.9)		23.71		0.0		22.12		(2.6)		22.18
Forfeited	(0.4)		22.55		0.0		23.14		(0.6)		21.12
Non-vested as of December 31, 2020	5.7		$	22.18	0.1		$	22.40	4.8		$	19.61
Total unrecognized compensation expense remaining	$	48.5			$	1.1			$	33.9
Weighted-average years expected to be recognized over	1.2				1.1				1.8

In conjunction with our annual grant of long-term incentive compensation awards, we reviewed our estimates and assumptions in 2020, which resulted in a forfeiture rate slightly less than prior years.

2009 and 2020 Restricted Cash Plan

In March 2009, the Compensation Committee approved the Interpublic Restricted Cash Plan and in November 2020, the Compensation Committee approved a new Interpublic Restricted Cash Plan, (collectively the “Cash Plans”). Under the Cash Plans, the Board, the Compensation Committee or the Plan Administrator may grant cash awards to certain employees eligible to receive cash-settled awards. Cash awards, when granted, have a service-period vesting condition and generally vest in two years or three years.

Cash Awards

During the years ended December 31, 2020, 2019 and 2018, the Compensation Committee granted cash awards under the Cash Plans with a total target value of $54.5, $22.3 and $20.9, respectively. For those same years, we recognized $25.5, $15.6 and $7.0, respectively, in salaries and related expenses in our Consolidated Statements of Operations.

During the years ended December 31, 2020, 2019 and 2018, the Compensation Committee granted performance awards to be settled in cash under the 2019 PIP with a total target value of $43.5, $40.7, and $39.9, respectively. For those same years, we recognized $29.2, $39.9 and $37.6, respectively, in salaries and related expenses in our Consolidated Statements of Operations.

We amortize the present value of the amount expected to vest for cash awards and performance cash awards over the vesting period using the straight-line method, less an assumed forfeiture rate. Cash awards do not fall within the scope of the authoritative guidance for stock compensation as they are not paid in equity and the value of the award is not correlated with our stock price. Due to the cash nature of the payouts and the vesting period, we account for these awards in accordance with authoritative guidance for deferred compensation arrangements.

Employee Stock Purchase Plans

In May 2016, our shareholders approved The Interpublic Group of Companies Employee Stock Purchase Plan (2016) (the “ESPP”), replacing the prior employee stock purchase plan under which, prior to its expiration on December 31, 2015, 3.0 shares were issued. Under the ESPP, eligible employees may purchase our common stock through payroll deductions not exceeding 10% of their eligible compensation or 900 (actual number) shares each offering period, consistent with the prior employee stock purchase plan. The price an employee pays for a share of common stock under the ESPP is 90% of the lesser of the average market price of a share on the first business day of the offering period or the average market price of a share on the last business day of the offering period of three months. An aggregate of approximately 10.0 shares are reserved for issuance under the ESPP, of which 1.6 shares have been issued since the inception of the ESPP through December 31, 2020.

Fair Value Measurements (Notes)

12 Months Ended

Dec. 31, 2020

Fair Value Disclosures [Abstract]

Fair Value Disclosures

Fair Value Measurements

Authoritative guidance for fair value measurements establishes a fair value hierarchy which requires us to maximize the use of observable inputs and minimize the use of unobservable inputs when measuring fair value. There are three levels of inputs that may be used to measure fair value:


Level 1						Unadjusted quoted prices in active markets for identical assets or liabilities. An active market for the asset or liability is a market in which transactions for the asset or liability occur with sufficient frequency and volume to provide pricing information on an ongoing basis.

Level 2						Observable inputs other than Level 1 prices, such as quoted prices for similar assets or liabilities; quoted prices in markets that are not active; or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the assets or liabilities.

Level 3						Unobservable inputs that are supported by little or no market activity and that are significant to the fair value of the assets or liabilities.

Financial Instruments that are Measured at Fair Value on a Recurring Basis

We primarily apply the market approach to determine the fair value of financial instruments that are measured at fair value on a recurring basis. There were no changes to our valuation techniques used to determine the fair value of financial instruments during 2020 as compared to the prior year.

The following tables present information about our financial instruments measured at fair value on a recurring basis as of December 31, 2020 and 2019, and indicates the fair value hierarchy of the valuation techniques utilized to determine such fair value.


	December 31, 2020								Balance Sheet Classification
	Level 1		Level 2		Level 3		Total
Assets
Cash equivalents 1	$	1,507.4	$	0.0	$	0.0	$	1,507.4	Cash and cash equivalents

Liabilities
Contingent acquisition obligations 2	$	0.0	$	0.0	$	95.5	$	95.5	Accrued liabilities and Other non-current liabilities

	December 31, 2019								Balance Sheet Classification
	Level 1		Level 2		Level 3		Total
Assets
Cash equivalents 1	$	786.0	$	0.0	$	0.0	$	786.0	Cash and cash equivalents

Liabilities
Contingent acquisition obligations 2	$	0.0	$	0.0	$	114.1	$	114.1	Accrued liabilities and Other non-current liabilities

1The increase from December 31, 2019 to December 31, 2020 in cash equivalents is related to increased U.S. investments in money market and time deposits driven by higher levels of excess cash near year-end.

2Contingent acquisition obligations includes deferred acquisition payments and unconditional obligations to purchase additional noncontrolling equity shares of consolidated subsidiaries. Fair value measurement of the obligations is based upon actual and projected operating performance targets as specified in the related agreements. The decrease in this balance of $18.6 from December 31, 2019 to December 31, 2020 is primarily due to payments. The amounts payable within the next twelve months are classified in accrued liabilities; any amounts payable thereafter are classified in other non-current liabilities.

Financial Instruments that are not Measured at Fair Value on a Recurring Basis

The following table presents information about our financial instruments that are not measured at fair value on a recurring basis as of December 31, 2020, and indicates the fair value hierarchy of the valuation techniques utilized to determine such fair value.


	December 31, 2020
	Level 1		Level 2		Level 3		Total
Total long-term debt	$	0.0	$	3,951.1	$	43.9	$	3,995.0

Our long-term debt is comprised of senior notes and other notes payable. The fair value of our senior notes, which are traded over-the-counter, is based on quoted prices in markets that are not active. Therefore, these senior notes are classified as Level 2. Our other notes payable are not actively traded, and their fair value is not solely derived from readily observable inputs. The fair value of our other notes payable is determined based on a discounted cash flow model and other proprietary valuation methods, and therefore is classified as Level 3. See Note 4 for further information on our long-term debt.

The discount rates used as significant unobservable inputs in the Level 3 fair value measurements of our contingent acquisition obligations and long-term debt as of December 31, 2020 ranged from 1.0% to 4.0% and 0.4% to 3.4%, respectively.

Non-financial Instruments that are Measured at Fair Value on a Nonrecurring Basis

Certain non-financial assets and liabilities are measured at fair value on a nonrecurring basis, primarily goodwill (Level 3), intangible assets, and property and equipment. Accordingly, these assets are not measured and adjusted to fair value on an ongoing basis but are subject to periodic evaluations for potential impairment.

- Definition

The entire disclosure for the fair value of financial instruments (as defined), including financial assets and financial liabilities (collectively, as defined), and the measurements of those instruments as well as disclosures related to the fair value of non-financial assets and liabilities. Such disclosures about the financial instruments, assets, and liabilities would include: (1) the fair value of the required items together with their carrying amounts (as appropriate); (2) for items for which it is not practicable to estimate fair value, disclosure would include: (a) information pertinent to estimating fair value (including, carrying amount, effective interest rate, and maturity, and (b) the reasons why it is not practicable to estimate fair value; (3) significant concentrations of credit risk including: (a) information about the activity, region, or economic characteristics identifying a concentration, (b) the maximum amount of loss the entity is exposed to based on the gross fair value of the related item, (c) policy for requiring collateral or other security and information as to accessing such collateral or security, and (d) the nature and brief description of such collateral or security; (4) quantitative information about market risks and how such risks are managed; (5) for items measured on both a recurring and nonrecurring basis information regarding the inputs used to develop the fair value measurement; and (6) for items presented in the financial statement for which fair value measurement is elected: (a) information necessary to understand the reasons for the election, (b) discussion of the effect of fair value changes on earnings, (c) a description of [similar groups] items for which the election is made and the relation thereof to the balance sheet, the aggregate carrying value of items included in the balance sheet that are not eligible for the election; (7) all other required (as defined) and desired information.

+ References + Details

Employee Benefits (Notes)

12 Months Ended

Dec. 31, 2020

Retirement Benefits [Abstract]

Employee Benefits

Pension and Postretirement Benefit Plans

We have a defined benefit pension plan covering certain U.S. employees (the “Domestic Pension Plan”) that consists of approximately 3,100 participants and is closed to new participants. We also have numerous funded and unfunded plans outside the U.S. The Interpublic Limited Pension Plan in the U.K. (the "U.K. Pension Plan") is a defined benefit plan and is our most material foreign pension plan in terms of the benefit obligation and plan assets. Some of our domestic and foreign subsidiaries provide postretirement health benefits and life insurance to eligible employees and, in certain cases, their dependents. The domestic postretirement benefit plan is our most material postretirement benefit plan in terms of the benefit obligation. This plan consists of approximately 1,400 participants, is closed to new participants and is unfunded.

Differences between the aggregate income statement and balance sheet amounts listed in the tables below and the totals reported in our Consolidated Statements of Operations, Consolidated Statements of Comprehensive Income and Consolidated Balance Sheets relate to non-material foreign pension and postretirement benefit plans.

Pension and Postretirement Benefit Obligation

The change in the benefit obligation, the change in plan assets, the funded status and amounts recognized for the Domestic Pension Plan, the significant foreign pension plans and the domestic postretirement benefit plan are listed below.


	Domestic Pension Plan				Foreign Pension Plans				Domestic Postretirement Benefit Plan

	2020		2019		2020		2019		2020		2019
Benefit Obligation
Projected benefit obligation as of January 1	$	116.9	$	115.4	$	541.2	$	496.0	$	27.2	$	27.7
Service cost	0.0		0.0		4.9		4.8		0.0		0.0
Interest cost	3.7		4.8		9.4		12.4		0.8		1.2
Benefits paid	(10.1)		(9.2)		(22.9)		(27.8)		(5.2)		(5.4)
Plan participant contributions	0.0		0.0		0.0		0.0		2.1		2.0
Actuarial losses	6.3		5.9		54.3		42.7		0.9		1.7
Settlements and curtailments	0.0		0.0		(4.9)		(0.7)		0.0		0.0
Foreign currency effect	0.0		0.0		23.3		13.8		0.0		0.0
Other	0.0		0.0		0.6		0.0		0.0		0.0

Projected benefit obligation as of December 31	$	116.8	$	116.9	$	605.9	$	541.2	$	25.8	$	27.2

Fair Value of Plan Assets
Fair value of plan assets as of January 1	$	99.1	$	89.8	$	409.5	$	363.9	$	0.0	$	0.0
Actual return on plan assets	10.6		16.1		45.7		42.0		0.0		0.0
Employer contributions	1.3		2.4		18.4		18.0		3.1		3.4
Plan participant contributions	0.0		0.0		0.0		0.0		2.1		2.0
Benefits paid	(10.1)		(9.2)		(22.9)		(27.8)		(5.2)		(5.4)
Settlements	0.0		0.0		(4.9)		0.0		0.0		0.0
Foreign currency effect	0.0		0.0		15.8		13.4		0.0		0.0

Fair value of plan assets as of December 31	$	100.9	$	99.1	$	461.6	$	409.5	$	0.0	$	0.0

Funded status of the plans at December 31	$	(15.9)	$	(17.8)	$	(144.3)	$	(131.7)	$	(25.8)	$	(27.2)


	Domestic Pension Plan				Foreign Pension Plans				Domestic Postretirement Benefit Plan
December 31,	2020		2019		2020		2019		2020		2019
Amounts recognized in Consolidated Balance Sheets
Non-current asset	$	0.0	$	0.0	$	10.9	$	10.1	$	0.0	$	0.0
Current liability	0.0		0.0		(7.4)		(5.8)		(2.5)		(2.7)
Non-current liability	(15.9)		(17.8)		(147.8)		(136.0)		(23.3)		(24.5)

Net liability recognized	$	(15.9)	$	(17.8)	$	(144.3)	$	(131.7)	$	(25.8)	$	(27.2)

Accumulated benefit obligation	$	116.8	$	116.9	$	603.3	$	538.6

Amounts recognized in Accumulated Other Comprehensive Loss, net
Net actuarial loss	$	53.9	$	54.2	$	213.3	$	183.2	$	5.4	$	4.7
Prior service cost (credit)	0.0		0.0		1.1		1.1		0.0		(0.1)

Total amount recognized	$	53.9	$	54.2	$	214.4	$	184.3	$	5.4	$	4.6

Actuarial losses of $6.3 for the Domestic Pension Plan are attributed to a decrease in the discount rate from 3.35% as of December 31, 2019 to 2.60% as of December 31, 2020, offset by changes in the mortality assumption and demographic experience. Actuarial losses of $54.3 for the foreign pension plans are attributed to a decrease in the weighted-average discount rate from 1.84% as of December 31, 2019 to 1.35% as of December 31, 2020 and changes in demographic experience.


	Domestic Pension Plan				Foreign Pension Plans
December 31,	2020		2019		2020		2019
Pension plans with an accumulated benefit obligation and projected benefit obligation in excess of plan assets
Aggregate projected benefit obligation	$	116.8	$	116.9	$	600.8	$	534.6
Aggregate accumulated benefit obligation	116.8		116.9		600.1		533.5
Aggregate fair value of plan assets	100.9		99.1		445.6		392.7

Net Periodic Cost

The components of net periodic benefit cost and key assumptions are listed below.


	Domestic Pension Plan						Foreign Pension Plans						Domestic Postretirement Benefit Plan
Years ended December 31,	2020		2019		2018		2020		2019		2018		2020		2019		2018
Service cost	$	0.0	$	0.0	$	0.0	$	4.9	$	4.8	$	5.4	$	0.0	$	0.0	$	0.0
Interest cost	3.7		4.8		4.5		9.4		12.4		13.1		0.8		1.2		1.1
Expected return on plan assets	(5.7)		(5.9)		(6.6)		(18.8)		(17.4)		(18.8)		0.0		0.0		0.0
Settlement and curtailment	0.0		0.0		0.0		(0.1)		0.0		(1.0)		0.0		0.0		0.0
Amortization of:
Prior service cost (credit)	0.0		0.0		0.0		0.1		0.1		0.1		0.0		(0.2)		(0.2)
Net actuarial losses	1.7		1.9		1.6		5.4		4.8		5.9		0.2		0.1		0.1
Net periodic cost	$	(0.3)	$	0.8	$	(0.5)	$	0.9	$	4.7	$	4.7	$	1.0	$	1.1	$	1.0

Assumptions


	Domestic Pension Plan						Foreign Pension Plans						Domestic Postretirement Benefit Plan
Years ended December 31,	2020		2019		2018		2020		2019		2018		2020		2019		2018

Net periodic cost
Discount rate	3.35	%	4.35	%	3.70	%	1.84	%	2.61	%	2.36	%	3.25	%	4.30	%	3.65	%
Rate of compensation increase	N/A		N/A		N/A		2.51	%	2.58	%	2.37	%	N/A		N/A		N/A
Expected return on plan assets	6.00	%	7.00	%	7.00	%	4.70	%	4.76	%	4.70	%	N/A		N/A		N/A
Interest crediting rates	5.10	%	5.10	%	5.10	%	1.37	%	1.44	%	1.31	%	N/A		N/A		N/A

Benefit obligation
Discount rate	2.60	%	3.35	%	4.35	%	1.35	%	1.84	%	2.61	%	2.50	%	3.25	%	4.30	%
Rate of compensation increase	N/A		N/A		N/A		2.47	%	2.51	%	2.58	%	N/A		N/A		N/A
Interest crediting rates	5.10	%	5.10	%	5.10	%	1.50	%	1.37	%	1.44	%	N/A		N/A		N/A

Health care cost trend rate assumed for next year
Initial rate (weighted-average)													6.75	%	7.00	%	6.25	%
Year ultimate rate is reached													2028		2028		2024
Ultimate rate													5.00	%	5.00	%	5.00	%

Discount Rates – At December 31, 2020, 2019 and 2018, we determined our discount rates for our domestic pension plan, foreign pension plans and domestic postretirement benefit plan based on either a bond selection/settlement approach or bond yield curve approach. Using the bond selection/settlement approach, we determine the discount rate by selecting a portfolio of corporate bonds appropriate to provide for the projected benefit payments. Using the bond yield curve approach, we determine the discount rate by matching the plans' cash flows to spot rates developed from a yield curve. Both approaches utilize high-quality AA-rated corporate bonds and the plans' projected cash flows to develop a discounted value of the benefit payments, which is then used to develop a single discount rate. In countries where markets for high-quality long-term AA corporate bonds are not well developed, a portfolio of long-term government bonds is used as a basis to develop hypothetical corporate bond yields, which serve as a basis to derive the discount rate.

Expected Return on Assets – Our expected rate of return is determined at the beginning of each year and considers asset class index returns over various market and economic conditions, current and expected market conditions, risk premiums associated with asset classes and long-term inflation rates. We determine both a short-term and long-term view and then select a long-term rate of return assumption that matches the duration of our liabilities.

Fair Value of Pension Plan Assets

The following table presents the fair value of our domestic and foreign pension plan assets as of December 31, 2020 and 2019, and indicates the fair value hierarchy of the valuation techniques utilized to determine such fair value. See Note 13 for a description of the fair value hierarchy.


	December 31, 2020								December 31, 2019
Plan assets subject to fair value hierarchy	Level 1		Level 2		Level 3		Total		Level 1		Level 2		Level 3		Total
Registered investment companies	$	19.3	$	0.0	$	0.0	$	19.3	$	18.0	$	0.0	$	0.0	$	18.0
Limited partnerships	0.0		0.0		25.9		25.9		0.0		0.0		25.6		25.6
Fixed income securities	22.7		0.0		0.0		22.7		19.6		0.0		0.0		19.6
Insurance contracts	0.0		3.6		0.0		3.6		0.0		5.5		0.0		5.5
Other	28.9		0.0		0.0		28.9		27.8		0.0		0.0		27.8
Total plan assets, subject to leveling	$	70.9	$	3.6	$	25.9	$	100.4	$	65.4	$	5.5	$	25.6	$	96.5
Plan assets measured at net asset value
Other investments measured at net asset value 1							462.1								412.1
Total plan assets							$	562.5							$	508.6

1Certain investments that are measured at fair value using the net asset value per share (or its equivalent) as a practical expedient have not been classified in the fair value hierarchy but are included to reconcile to the amounts presented in the fair value of plan assets table above.

Registered investment companies, which are publicly traded, are primarily valued using recently reported sales prices. Limited partnerships are invested primarily in equity and fixed income securities. Fixed income securities include government and investment-grade corporate bonds. Insurance contracts are valued based on the cash surrender value of the contract. Other investments primarily include cash and cash equivalents, equity securities and derivatives. Other investments measured at net asset value include common/collective trusts, hedge funds and other commingled assets that are invested primarily in equity and fixed income securities. These investments are not publicly traded and are valued based on the net asset value of shares held by the plan at year end, which reflects the fair value of the underlying investments.

The following table presents additional information about our significant foreign pension plan assets for which we utilize Level 3 inputs to determine fair value.


	Years ended December 31,
Plan assets subject to fair value hierarchy, Level 3	2020		2019

Balance at beginning of period	$	25.6	$	25.6
Actual return on plan assets	0.3		0.0


Balance at end of period	$	25.9	$	25.6

Asset Allocation

The primary investment goal for our plans’ assets is to maximize total asset returns while ensuring the plans’ assets are available to fund the plans’ liabilities as they become due. The plans’ assets in aggregate and at the individual portfolio level are invested so that total portfolio risk exposure and risk-adjusted returns best achieve this objective. The aggregate amount of our own stock held as investment for our domestic and foreign pension funds is considered negligible relative to the total fund assets. As of December 31, 2020, the weighted-average target and actual asset allocations relating to our domestic and foreign pension plans' assets are listed below.


			December 31,
Asset Class	2021 Target Allocation		2020		2019
Alternative investments 1	23	%	24	%	25	%
Equity securities	27	%	27	%	25	%
Fixed income securities	19	%	18	%	19	%
Liability driven investments 2	15	%	15	%	14	%
Real estate	9	%	9	%	9	%
Other	7	%	7	%	8	%
Total	100	%	100	%	100	%

1Alternative investments have the flexibility to dynamically invest across a broad range of asset classes including bonds, equity, cash, property and commodities.

2Liability driven investment strategies use government bonds as well as derivative instruments to hedge a portion of the impact of interest rates and inflation movements on the long-term liabilities.

Cash Flows

During 2020, we contributed $1.3 and $18.4 of cash to our domestic and foreign pension plans, respectively. For 2021, we expect to contribute approximately $3.0 and $19.0 of cash to our domestic and foreign pension plans, respectively.

The estimated future benefit payments expected to be paid are presented below.


Years	Domestic Pension Plan		Foreign Pension Plans		Domestic Postretirement Benefit Plan
2021	$	10.2	$	25.0	$	2.5
2022	8		22.9		2.3
2023	7.5		24.0		2.1
2024	7.5		25.2		2.0
2025	7.4		25.9		1.8
2026 - 2030	34.2		129.5		8.0

The estimated future payments for our domestic postretirement benefit plan are net of any estimated U.S. federal subsidies expected to be received under the Medicare Prescription Drug, Improvement and Modernization Act of 2003, which total no more than $0.2 in any individual year.

Savings Plans

We sponsor defined contribution plans (the “Savings Plans”) that cover substantially all domestic employees. The Savings Plans permit participants to make contributions on a pre-tax and/or after-tax basis and allow participants to choose among various investment alternatives. We match a portion of participant contributions based upon their years of service. Amounts expensed for the Savings Plans for 2020, 2019 and 2018 were $58.7, $61.2 and $52.6, respectively. Expenses include a discretionary Company contribution of $2.9, $8.1 and $6.7 offset by participant forfeitures of $5.1, $5.6 and $5.8 in 2020, 2019 and 2018, respectively. In addition, we maintain defined contribution plans in various foreign countries and contributed $46.3, $54.5 and $51.3 to these plans in 2020, 2019 and 2018, respectively.

Deferred Compensation and Benefit Arrangements

We have deferred compensation and benefit arrangements which (i) permit certain of our key officers and employees to defer a portion of their salary or incentive compensation or (ii) require us to contribute an amount to the participant’s account. These arrangements may provide participants with the amounts deferred plus interest upon attaining certain conditions, such as completing a certain number of years of service, attaining a certain age or upon retirement or termination. As of December 31, 2020 and 2019, the deferred compensation and deferred benefit liability balance was $188.5 and $197.5, respectively. Amounts expensed for deferred compensation and benefit arrangements in 2020, 2019 and 2018 were $11.0, $19.4 and $10.0, respectively.

We have purchased life insurance policies on participants' lives to assist in the funding of the related deferred compensation and deferred benefit liabilities. As of December 31, 2020 and 2019, the cash surrender value of these policies was $180.8 and $178.2, respectively.

Long-Term Disability Plan

We have a long-term disability plan which provides income replacement benefits to eligible participants who are unable to perform their job duties or any job related to his or her education, training or experience. As all income replacement benefits are fully insured, no related obligation is required as of December 31, 2020 and 2019. In addition to income replacement benefits, plan participants may remain covered for certain health and life insurance benefits up to normal retirement age, and accordingly, we have recorded an obligation of $8.7 and $5.5 as of December 31, 2020 and 2019, respectively.

- Definition

The entire disclosure for retirement benefits.

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+ Details

Segment Information (Notes)

12 Months Ended

Dec. 31, 2020

Segment Reporting [Abstract]

Segment Information

As of December 31, 2020, we have two reportable segments: IAN and DXTRA. IAN is comprised of McCann Worldgroup, Foote, Cone & Belding ("FCB"), MullenLowe Group, Media, Data Services and Tech, which includes IPG Mediabrands, Acxiom and Kinesso, our digital specialist agencies and our domestic integrated agencies. DXTRA is comprised of a number of our specialist marketing services offerings including Weber Shandwick, DeVries, Golin, FutureBrands, Jack Morton and Octagon Worldwide. We also report results for the "Corporate and other" group.

Within IAN, our agencies provide a comprehensive array of global communications and marketing services, each offering a range of solutions for our clients. Our digital specialist agencies, including R/GA and Huge, provide digital capabilities and serve as key digital partners. In addition, our domestic integrated agencies, including Hill Holliday, Deutsch, Carmichael Lynch and Tierney, provide a full range of advertising, marketing communications services and/or marketing services and partner with our global operating divisions as needed. Media, Data Services and Tech offerings provide strategic media planning and buying services as well as data management and leading marketing technology services. IAN’s operating divisions share similar economic characteristics and are similar in other areas, specifically related to the nature of their services, the manner in which the services are provided and the similarity of their respective customers.

DXTRA, which includes Weber Shandwick, DeVries, Golin, FutureBrand, Jack Morton and Octagon Worldwide, provides clients with diversified services, including public relations, meeting and event production, sports and entertainment marketing, corporate and brand identity, and strategic marketing consulting. DXTRA shares some similarities with service lines offered by IAN; however, on an aggregate basis, DXTRA has a higher proportion of arrangements for which they act as principal.

Beginning in the first quarter of 2019, Acxiom's results are presented in IAN and the profitability measure employed by our chief operating decision maker for allocating resources to operating divisions and assessing operating division performance is segment EBITA. All segments follow the same accounting policies as those described in Note 1.

Corporate and other is primarily comprised of selling, general and administrative expenses. Selling, general and administrative expenses includes corporate office expenses as well as shared service center and certain other centrally managed expenses that are not fully allocated to operating divisions; salaries, long-term incentives, annual bonuses and other miscellaneous benefits for corporate office employees; professional fees related to internal control compliance, financial statement audits and legal, information technology and other consulting services that are engaged and managed through the corporate office; and rental expense for properties occupied by corporate office employees. A portion of centrally managed expenses is allocated to operating divisions based on a formula that uses the planned revenues of each of the operating units. Amounts allocated also include specific charges for information technology-related projects, which are allocated based on utilization.

Summarized financial information concerning our reportable segments is shown in the following tables.


	Years ended December 31,
	2020		2019		2018
Total Revenue:
IAN	$	7,410.1	$	7,992.0	$	7,427.3
DXTRA	1,650.9		2,229.3		2,287.1
Total	$	9,061.0	$	10,221.3	$	9,714.4

Net revenue:
IAN	$	6,921.4	$	7,328.8	$	6,720.9
DXTRA	1,143.1		1,296.3		1,310.7
Total	$	8,064.5	$	8,625.1	$	8,031.6

Segment EBITA 1:
IAN	$	699.1	$	1,115.7	$	1,038.8
DXTRA	56.5		158.1		183.6
Corporate and other	(81.3)		(101.8)		(176.0)
Total	$	674.3	$	1,172.0	$	1,046.4

Amortization of acquired intangibles:
IAN	$	81.5	$	81.6	$	32.2
DXTRA	4.4		4.4		5.4
Corporate and other	0.0		0.0		0.0
Total	$	85.9	$	86.0	$	37.6

Depreciation and amortization 2:
IAN	$	178.9	$	164.6	$	136.0
DXTRA	20.4		20.6		19.8
Corporate and other	5.4		7.3		9.5
Total	$	204.7	$	192.5	$	165.3

Capital expenditures:
IAN	$	132.0	$	161.8	$	143.7
DXTRA	8.4		13.3		13.2
Corporate and other	27.1		23.4		20.2
Total	$	167.5	$	198.5	$	177.1

1 Adjusted EBITA is calculated as net income available to IPG common stockholders before provision for income taxes, total (expenses) and other income, equity in net income (loss) of unconsolidated affiliates, net income attributable to noncontrolling interests and amortization of acquired intangibles.

2 Excludes amortization of acquired intangibles.


	December 31,
	2020		2019
Total assets:
IAN	$	14,784.5	$	15,155.2
DXTRA	1,549.2		1,725.5
Corporate and other	1,709.0		871.2
Total	$	18,042.7	$	17,751.9

The following table presents the reconciliation of segment EBITA to Income before income taxes.


	Years ended December 31,
	2020		2019		2018
IAN EBITA	$	699.1	$	1,115.7	$	1,038.8
DXTRA EBITA	56.5		158.1		183.6
Corporate and other EBITA	(81.3)		(101.8)		(176.0)
Less: consolidated amortization of acquired intangibles	85.9		86.0		37.6
Operating income	588.4		1,086.0		1,008.8
Total (expenses) and other income	(227.1)		(207.7)		(170.8)
Income before income taxes	$	361.3	$	878.3	$	838.0

Long-lived assets, including operating lease right-of-use assets and excluding intangible assets, are presented by major geographic area in the following table.


	Long-Lived Assets
	December 31,
	2020		2019
Domestic	$	1,801.4	$	2,080.4
International:
United Kingdom	216.6		167.6
Continental Europe	117.5		149.7
Asia Pacific	183.1		240.9
Latin America	58.9		74.8
Other	116.5		130.4
Total International	692.6		763.4
Total Consolidated	$	2,494.0	$	2,843.8

Property and equipment are allocated based upon physical location. Other assets and investments are allocated based on the location of the related operations.

- Definition

The entire disclosure for reporting segments including data and tables. Reportable segments include those that meet any of the following quantitative thresholds a) it's reported revenue, including sales to external customers and intersegment sales or transfers is 10 percent or more of the combined revenue, internal and external, of all operating segments b) the absolute amount of its reported profit or loss is 10 percent or more of the greater, in absolute amount of 1) the combined reported profit of all operating segments that did not report a loss or 2) the combined reported loss of all operating segments that did report a loss c) its assets are 10 percent or more of the combined assets of all operating segments.

+ References

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+ Details

Commitments and Contingencies (Notes)

12 Months Ended

Dec. 31, 2020

Commitments and Contingencies Disclosure [Abstract]

Commitments and Contingencies

Guarantees

We have guaranteed certain obligations of our subsidiaries relating principally to operating leases and uncommitted lines of credit of certain subsidiaries. As of December 31, 2020 and 2019, the amount of parent company guarantees on lease obligations was $630.8 and $739.1, respectively, the amount of parent company guarantees primarily relating to uncommitted lines of credit was $399.6 and $293.8, respectively, and the amount of parent company guarantees related to daylight overdrafts, primarily utilized to manage intra-day overdrafts due to timing of transactions under cash pooling arrangements without resulting in incremental borrowings, was $109.2 and $207.7, respectively. In the event of non-payment by the applicable subsidiary of the obligations covered by a guarantee, we would be obligated to pay the amounts covered by that guarantee. As of December 31, 2020, there were no material assets pledged as security for such parent company guarantees.

Contingent Acquisition Obligations

The following table details the estimated future contingent acquisition obligations payable in cash as of December 31, 2020.


	2021		2022		2023		2024		2025		Thereafter		Total
Deferred acquisition payments	$	47.9	$	10.9	$	7.0	$	8.4	$	0.0	$	2.9	$	77.1
Redeemable noncontrolling interests and call options with affiliates 1	17.2		23.3		26.8		1.5		0.7		0.0		69.5
Total contingent acquisition payments	$	65.1	$	34.2	$	33.8	$	9.9	$	0.7	$	2.9	$	146.6

1We have entered into certain acquisitions that contain both redeemable noncontrolling interests and call options with similar terms and conditions. The estimated amounts listed would be paid in the event of exercise at the earliest exercise date. We have certain redeemable noncontrolling interests that are exercisable at the discretion of the noncontrolling equity owners as of December 31, 2020. These estimated payments of $14.2 are included within the total payments expected to be made in 2021, and will continue to be carried forward into 2022 or beyond until exercised or expired. Redeemable

noncontrolling interests are included in the table at current exercise price payable in cash, not at applicable redemption value, in accordance with the authoritative guidance for classification and measurement of redeemable securities.

The majority of these payments are contingent upon achieving projected operating performance targets and satisfying other conditions specified in the related agreements and are subject to revision in accordance with the terms of the respective agreements. See Note 6 for further information relating to the payment structure of our acquisitions.

Legal Matters

We are involved in various legal proceedings, and subject to investigations, inspections, audits, inquiries and similar actions by governmental authorities arising in the normal course of business. The types of allegations that arise in connection with such legal proceedings vary in nature, but can include claims related to contract, employment, tax and intellectual property matters. We evaluate all cases each reporting period and record liabilities for losses from legal proceedings when we determine that it is probable that the outcome in a legal proceeding will be unfavorable and the amount, or potential range, of loss can be reasonably estimated. In certain cases, we cannot reasonably estimate the potential loss because, for example, the litigation is in its early stages. While any outcome related to litigation or such governmental proceedings in which we are involved cannot be predicted with certainty, management believes that the outcome of these matters, individually and in the aggregate, will not have a material adverse effect on our financial condition, results of operations or cash flows.

Recent Accounting Standards (Notes)	12 Months Ended
Recent Accounting Standards (Notes)	Dec. 31, 2020
Accounting Standards Update and Change in Accounting Principle [Abstract]
Recent Accounting Standards	Recent Accounting Standards Accounting pronouncements not listed below were assessed and determined to be not applicable or are expected to have minimal impact on our Consolidated Financial Statements. Current Expected Credit Losses In June 2016, the Financial Accounting Standards Board ("FASB") issued amended guidance on the accounting for credit losses on certain types of financial instruments, including trade receivables. The new model uses a forward-looking expected loss method, as opposed to the incurred loss method in current U.S. GAAP, which will generally result in earlier recognition of allowances for losses. We adopted this standard using the modified retrospective approach with an effective date of January 1, 2020. The adoption of this amended guidance did not have a material impact on our Consolidated Financial Statements. Fair Value Measurement Disclosures In August 2018, the FASB issued amended disclosure requirements for fair value measurements by removing, modifying and adding certain disclosures. This amended guidance was effective beginning January 1, 2020. The adoption of this amended guidance did not have a material impact on our Consolidated Financial Statements. Income Taxes In December 2019, the FASB issued amended guidance to simplify the accounting for income taxes by removing certain exceptions and amending certain sections of existing guidance under ASC 740. This amended guidance is effective January 1, 2021. We do not expect the adoption of this amended guidance to have a material impact on our Consolidated Financial Statements.

Results by Quarter (Unaudited) (Notes)

12 Months Ended

Dec. 31, 2020

Quarterly Financial Information Disclosure [Abstract]

Quarterly Financial Information

Results by Quarter (Unaudited)


	Three Months Ended March 31,				Three Months Ended June 30,				Three Months Ended September 30,				Three Months Ended December 31,
	2020		2019		2020		2019		2020		2019		2020		2019
Revenue:
Net revenue	$	1,972.1	$	2,004.8	$	1,853.4	$	2,125.9	$	1,954.6	$	2,061.4	$	2,284.4	$	2,433.0
Billable expenses	387.7		356.4		172.3		394.3		170.9		376.7		265.6		468.8
Total Revenue	2,359.8		2,361.2		2,025.7		2,520.2		2,125.5		2,438.1		2,550.0		2,901.8

Operating Expenses:
Salaries and related expenses	1,422.8		1,421.1		1,306.1		1,381.2		1,269.9		1,334.4		1,346.2		1,432.1
Office and other direct expenses	378.2		389.2		317.0		387.3		307.9		367.9		364.8		419.7
Billable expenses	387.7		356.4		172.3		394.3		170.9		376.7		265.6		468.8
Cost of services	2,188.7		2,166.7		1,795.4		2,162.8		1,748.7		2,079.0		1,976.6		2,320.6
Selling, general and administrative expenses	22.4		41.4		4.1		18.1		9.9		9.8		22.4		24.5
Depreciation and amortization	72.8		71.1		73.1		73.0		71.0		69.0		73.7		65.4
Restructuring Charges 1	0.0		31.8		112.6		2.1		47.3		0.0		253.9		0.0
Total operating expenses	2,283.9		2,311.0		1,985.2		2,256.0		1,876.9		2,157.8		2,326.6		2,410.5
Operating income	75.9		50.2		40.5		264.2		248.6		280.3		223.4		491.3
Net interest expense	(34.1)		(42.0)		(43.9)		(43.9)		(44.7)		(40.2)		(40.0)		(38.7)
Other expense, net 2	(21.8)		(6.9)		(21.5)		(3.8)		(11.3)		(7.4)		(9.8)		(24.8)
Total (expenses) and other income	(55.9)		(48.9)		(65.4)		(47.7)		(56.0)		(47.6)		(49.8)		(63.5)
Provision for (benefit of) for income taxes 3	17.2		10.5		19.0		43.6		(86.3)		64.6		58.1		86.1
Net income (loss)	2.6		(9.5)		(43.9)		172.8		278.5		168.4		117.0		342.2
Net income (loss) available to IPG common stockholders	$	4.7	$	(8.0)	$	(45.6)	$	169.5	$	279.7	$	165.6	$	112.3	$	328.9
Earnings (loss) per share available to IPG common stockholders:
Basic	$	0.01	$	(0.02)	$	(0.12)	$	0.44	$	0.72	$	0.43	$	0.29	$	0.85
Diluted	$	0.01	$	(0.02)	$	(0.12)	$	0.43	$	0.71	$	0.42	$	0.28	$	0.84
Dividends declared per common share	$	0.255	$	0.235	$	0.255	$	0.235	$	0.255	$	0.235	$	0.255	$	0.235

1The three months ended June 30, September 30 and December 31, 2020 included restructuring charges of $112.6, $47.3 and $253.9, respectively. The three months ended March 31 and June 30, 2019 included restructuring charges of $31.8 and $2.1, respectively. See "Restructuring Charges" Note 11 for further information.

2The three months ended March 31, June 30 September 30 and December 31, 2020 included pre-tax net losses of $23.3, $19.9, $8.6, and $15.2, respectively, on sales of businesses. The three months ended March 31, June 30, September 30 and December 31, 2019 included pre-tax net losses of $8.6, $3.2, $7.7, and $23.9, respectively, on sales of businesses.

3The three months ended June 30 and September 30, 2020 included tax expense of $10.4 and $3.2, respectively, related to a change in our indefinite reinvestment assertion for certain foreign subsidiaries (APB 23). The three months ended September 30, 2020 also included a net tax benefit of $136.2 related to the settlement of the U.S. Federal income tax audit of the years 2006 through 2016. The three months ended June 30 and December 31, 2019 included a tax benefit of $13.9 related to the settlement of certain tax positions and $25.3 related to valuation allowance reversals, respectively.

Subsequent Events (Notes)	12 Months Ended
Subsequent Events (Notes)	Dec. 31, 2020
Subsequent Events [Abstract]
Subsequent Events [Text Block]	Subsequent EventsWe announced on February 10, 2021 that our Board had declared a common stock cash dividend of $0.27 per share, payable on March 15, 2021 to holders of record as of the close of business on March 1, 2021.

Significant Accounting Policies Basis of Presentation (Policies)	12 Months Ended
	Dec. 31, 2020
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Organization, Consolidation and Presentation of Financial Statements Disclosure [Text Block]	Basis of Presentation Cost of services is comprised of the expenses of our revenue-producing operating segments including salaries and related expenses, office and other direct expenses and billable expenses, as well as an allocation of the centrally managed expenses from Corporate and other. Office and other direct expenses include rent expense, professional fees, certain expenses incurred by our staff in servicing our clients and other costs directly attributable to client engagements. Selling, general and administrative expenses are primarily the unallocated expenses from Corporate and other, as disclosed further in Note 15, excluding depreciation and amortization. Depreciation and amortization of the fixed assets and intangible assets of the Company is disclosed as a separate operating expense. Restructuring charges relate to the Company's implementation of a cost initiative to better align our cost structure with our revenue, as discussed further in Note 11.
Lessee, Leases [Policy Text Block]	Leases Effective January 1, 2019, we adopted Accounting Standards Codification Topic 842, Leases (ASC 842), using the modified retrospective transition method. As such, we recognized a right-of-use asset and a corresponding lease liability on our Consolidated Balance Sheet for virtually all of our leases with a term of more than twelve months. Consolidated financial statements for the year ended December 31, 2018 were not recast under the new standard. As an accounting policy, we have elected not to apply the recognition requirements to short-term leases, not to separate non-lease components from lease components, and have elected the package of transition provisions available for existing contracts, which allowed us to carry forward our historical assessments of (i) whether contracts are or contain leases, (ii) lease classification and (iii) initial direct costs. The adoption of ASC 842 resulted in operating lease right-of-use assets of $1,421.1 and operating lease liabilities of $1,544.4 as of January 1, 2019. As of December 31, 2020, we do not have a material amount of finance leases and the majority of our operating leases, for which we serve as the lessee, consist primarily of real-estate property for our offices around the world. Both the right-of-use asset and lease liability are measured at the present value of the future lease payments, with the asset being subject to adjustments such as initial direct costs, prepaid lease payments, and lease incentives. Many of our leases provide for renewal and/or termination options, as well as escalation clauses, which are also factored into our lease payments when appropriate. The discount rate used to measure the lease asset and liability is determined at the beginning of the lease term using the rate implicit in the lease, if readily determinable, or using the Company's collateralized credit-adjusted borrowing rate.

Significant Accounting Policies Principles of Consolidation (Policies)	12 Months Ended
	Dec. 31, 2020
Accounting Policies [Abstract]
Principles of Consolidation	Principles of Consolidation The Consolidated Financial Statements include the accounts of the Company and its consolidated subsidiaries, some of which are not wholly owned. Investments in companies over which we do not have control, but have the ability to exercise significant influence, are accounted for using the equity method of accounting. Investments in companies over which we have neither control nor have the ability to exercise significant influence are recorded at cost, less any impairment, adjusted for subsequent observable price changes. All intercompany accounts and transactions have been eliminated in consolidation. We have consolidated certain entities meeting the definition of variable interest entities, and the inclusion of these entities does not have a material impact on our Consolidated Financial Statements.

Significant Accounting Policies Reclassifications (Policies)	12 Months Ended
	Dec. 31, 2020
Accounting Policies [Abstract]
Reclassifications	Reclassifications Certain reclassifications and immaterial changes have been made to prior-period financial statements to conform to the current-period presentation. Segment information for the prior period has been recast to conform to the current-period presentation.

Significant Accounting Policies Use of Estimates (Policies)	12 Months Ended
	Dec. 31, 2020
Accounting Policies [Abstract]
Use of Estimates	Use of Estimates The preparation of financial statements in conformity with accounting principles generally accepted in the United States of America (“U.S. GAAP”) requires us to make judgments, assumptions and estimates that affect the amounts of assets and liabilities, the disclosure of contingent assets and liabilities at the reporting date and the reported amounts of revenues and expenses during the reporting period. Actual results could differ from these estimates and assumptions.

Significant Accounting Policies Revenue Recognition (Policies)	12 Months Ended
	Dec. 31, 2020
Accounting Policies [Abstract]
Revenue Recognition	Revenue Recognition Our revenues are primarily derived from the planning and execution of multi-channel advertising and communications, marketing services, including public relations, meeting and event production, sports and entertainment marketing, corporate and brand identity, strategic marketing consulting, and providing marketing data and technology services around the world. Most of our client contracts are individually negotiated and, accordingly, the terms of client engagements and the basis on which we earn fees and commissions vary significantly. Our contracts generally provide for termination by either party on relatively short notice, usually 30 to 90 days, although our data management contracts typically have non-cancelable terms of more than one year. Our payment terms vary by client, and the time between invoicing date and due date is typically not significant. We generally have the legally enforceable right to payment for all services provided through the end of the contract or termination date. We recognize revenue when we determine our customer obtains control of promised goods or services, in an amount that reflects the consideration which we expect to receive in exchange for those goods or services. To determine revenue recognition, we perform the following five steps: (i) identify the contract(s) with a customer; (ii) identify the performance obligations in the contract; (iii) determine the transaction price; (iv) allocate the transaction price to the performance obligations in the contract; and (v) recognize revenue as or when we satisfy the performance obligation. We only apply the five-step model to contracts when it is probable that IPG will collect the consideration it is entitled to in exchange for the goods or services it transfers to the customer. At contract inception, we assess the goods or services promised within each contract and determine those that are distinct performance obligations. We then assess whether we act as an agent or a principal for each identified performance obligation and include revenue within the transaction price for third-party costs when we determine that we act as principal. We typically do not capitalize costs to obtain a contract as these amounts would generally be recognized over a period of one year or less. Net revenue, primarily consisting of fees, commissions and performance incentives, represents the amount of our gross billings excluding billable expenses charged to a client. Generally, our compensation is based on a negotiated fixed price, rate per hour, a retainer, commission or volume. The majority of our fees are recognized over time as services are performed, either utilizing a function of hours incurred and rates per hour, as compared to periodically updated estimates to complete, or ratably over the term of the contract. For certain less-frequent commission-based contracts which contain clauses allowing our clients to terminate the arrangement at any time for no compensation, revenue is recognized at a point in time, typically the date of broadcast or publication. We report revenue net of taxes assessed by governmental authorities that are directly imposed on our revenue-producing transactions. Contractual arrangements with clients may also include performance incentive provisions designed to link a portion of our revenue to our performance relative to mutually agreed-upon qualitative and/or quantitative metrics. Performance incentives are treated as variable consideration which is estimated at contract inception and included in revenue based on the most likely amount earned out of a range of potential outcomes. Our estimates are based on a combination of historical award experience, anticipated performance and our best judgment. These estimates are updated on a periodic basis and are not expected to result in a reversal of a significant amount of the cumulative revenue recognized. The predominant component of billable expenses are third-party vendor costs incurred for performance obligations where we have determined that we are acting as principal. These third-party expenses are generally billed back to our clients. Billable expenses also includes incidental costs incurred in the performance of our services including airfare, mileage, hotel stays, out-of-town meals and telecommunication charges. We record these billable expenses within total revenue with a corresponding offset to operating expenses. In international markets, we may receive rebates or credits from vendors based on transactions entered into on behalf of clients. Rebates and credits are remitted back to our clients in accordance with our contractual requirements or may be retained by us based on the terms of a particular client contract and local law. Amounts owed back to clients are recorded as a liability and amounts retained by us are recorded as revenue when earned. In certain international markets, our media contracts may allow clients to terminate our arrangement at any time for no compensation to the extent that media has not yet run. For those contracts, we do not recognize revenue until the media runs which is the point in time at which we have a legally enforceable right to compensation. Performance Obligations Our client contracts may include various goods and services that are capable of being distinct, are distinct within the context of the contract and are therefore accounted for as separate performance obligations. We allocate revenue to each performance obligation in the contract at inception based on its relative standalone selling price. Our advertising businesses include a wide range of services that involve the creation of an advertising idea, concept, campaign, or marketing strategy in order to promote the client’s brand ("creative services"), and to act as an agent to facilitate the production of advertisements by third-party suppliers ("production services”). Our clients can contract us to perform one or both of these services, as they can derive stand-alone benefit from each. Production services can include formatting creative material for different media and communication mediums including digital, large-scale reproduction such as printing and adaptation services, talent engagement and acquisition, television and radio production, and outdoor billboard production. Our contracts that include both services are typically explicit in the description of which activities constitute the creative advertising services and those that constitute the production services. Both the creative and production services are sold separately, the client can derive utility from each service on its own, we do not provide a significant service of integrating these activities into a bundle, the services do not significantly modify one another, and the services are not highly interrelated or interdependent. As such, we typically identify two performance obligations in the assessment of our advertising contracts. Our media businesses include services to formulate strategic media plans ("media planning services") and to act as an agent to purchase media (e.g. television and radio spots, outdoor advertising, digital banners, etc.) from vendors on our clients' behalf ("media buying services"). Our contracts that include both services are typically explicit in the description of which activities constitute the planning services and those that constitute the buying services. Both the planning and buying services are sold separately, the client can derive utility from each service on its own, we do not provide a significant service of integrating these activities into a bundle, the services do not significantly modify one another, and the services are not highly interrelated or interdependent. As such, we typically identify two performance obligations in the assessment of our media contracts. Our events businesses include creative services related to the conception and planning of custom marketing events as well as activation services which entail the carrying out of the event, including, but not limited to, set-up, design and staffing. Additionally, our public relations businesses include a broad range of services, such as strategic planning, social media strategy and the monitoring and development of communication strategies, among others. While our contracts in these businesses may include some or all of these services, we typically identify only one performance obligation in the assessment of our events and public relations contracts as we provide a significant service of integrating the individual services into a combined service for which the customer has contracted. Our data and technology services businesses include data management, data and data strategy, identity resolution, and measurement and analytics products and services. While our contracts in these businesses may include some or all of these services, we typically identify each product and service as an individual performance obligation. We have elected not to disclose information about remaining performance obligations that have original expected durations of one year or less. The majority of our contracts are for periods of one year or less with the exception of our data management contracts. Principal vs. Agent When a third-party is involved in the delivery of our services to the client, we assess whether or not we are acting as a principal or an agent in the arrangement. The assessment is based on whether we control the specified services at any time before they are transferred to the customer. We have determined that in our events and public relations businesses, we generally act as a principal as our agencies provide a significant service of integrating goods or services provided by third parties into the specified deliverable to our clients. In addition, we have determined that we are responsible for the performance of the third-party suppliers, which are combined with our own services, before transferring those services to the customer. We have also determined that we act as principal when providing creative services and media planning services, as we perform a significant integration service in these transactions. For performance obligations in which we act as principal, we record the gross amount billed to the customer within total revenue and the related incremental direct costs incurred as billable expenses. When a third-party is involved in the production of an advertising campaign and for media buying services, we have determined that we act as the agent and are solely arranging for the third-party suppliers to provide services to the customer. Specifically, we do not control the specified services before transferring those services to the customer, we are not primarily responsible for the performance of the third-party services, nor can we redirect those services to fulfill any other contracts. We do not have inventory risk or discretion in establishing pricing in our contracts with customers. For performance obligations for which we act as the agent, we record our revenue as the net amount of our gross billings less amounts remitted to third parties.

Significant Accounting Policies Cash and Cash Equivalents (Policies)	12 Months Ended
	Dec. 31, 2020
Accounting Policies [Abstract]
Cash and Cash Equivalents	Cash and Cash Equivalents Cash equivalents are highly liquid investments, which include certificates of deposit, government securities, commercial paper and time deposits with original maturities of three months or less at the time of purchase and are stated at estimated fair value, which approximates cost. Cash is maintained at multiple high-credit-quality financial institutions.

Significant Accounting Policies Allowance for Doubtful Accounts (Policies)	12 Months Ended
	Dec. 31, 2020
Accounting Policies [Abstract]
Allowance for Doubtful Accounts	Allowance for Expected Credit Losses We adopted Accounting Standards Codification Topic 326, Current Expected Credit Losses, on January 1, 2020 using the modified retrospective transition method. The allowance for credit losses on expected future uncollectible accounts receivable is estimated based on the aging of accounts receivable, reviews of client credit reports, industry trends and economic indicators, as well as reviews of recent payment history for specific customers. The estimate is based largely on a formula-driven calculation but is supplemented with economic indicators and knowledge of potential write-offs of specific client accounts.

Significant Accounting Policies Acounts Receivable, Billable to Clients (Policies)	12 Months Ended
	Dec. 31, 2020
Accounting Policies [Abstract]
Accounts Receivable, Billable to Clients	Accounts Receivable, Billable to Clients Accounts receivable, billable to clients are primarily comprised of production and media costs that have been incurred but have not yet been billed to clients, as well as fees that have been earned which have not yet been billed to clients. Unbilled amounts are presented in expenditures billable to clients regardless of whether they relate to our fees or production and media costs. A provision is made for unrecoverable costs as deemed appropriate.

Significant Accounting Policies Accounts Payable (Policies)	12 Months Ended
	Dec. 31, 2020
Accounting Policies [Abstract]
Accounts Payable	Accounts PayableAccounts payable includes all operating payables, including those related to all media and production costs. These payables are due within one year.

Significant Accounting Policies Investments (Policies)	12 Months Ended
Significant Accounting Policies Investments (Policies)	Dec. 31, 2020
Accounting Policies [Abstract]
Investments	Investments Equity investments with readily determinable fair values, other than those accounted for using the equity method of accounting, will be measured at fair value. We regularly review our investments to determine whether a significant event or change in circumstances has occurred that may impact the fair value of each investment, with changes to fair value recorded in earnings. We evaluate fair value based on specific information (valuation methodologies, estimates of appraisals, financial statements, etc.) in addition to quoted market price, if available. We consider all known quantitative and qualitative factors in determining if a decline in value of an investment has occurred.

Significant Accounting Policies Derivatives (Policies)	12 Months Ended
Significant Accounting Policies Derivatives (Policies)	Dec. 31, 2020
Accounting Policies [Abstract]
Derivatives	DerivativesWe are exposed to market risk related to interest rates, foreign currency rates and certain balance sheet items. From time to time we enter into derivative instruments for risk management purposes, and not for speculative purposes. All derivative instruments are recorded at fair value on our balance sheet. Changes in fair value are immediately included in earnings if the derivatives are not designated as a hedge instrument or if the derivatives do not qualify as effective hedges. For derivatives designated as hedge instruments, we evaluate for hedge accounting both at inception and throughout the hedge period. If a derivative is designated as a fair value hedge, then changes in the fair value of the derivative are offset against the changes in the fair value of the underlying hedged item. If a derivative is designated as a cash flow hedge, then the changes in the fair value of the derivative are recognized as a component of accumulated other comprehensive income and subsequently reclassified to earnings in our Consolidated Statement of Operations in the same period as the underlying hedged transaction affects earnings. If a derivative is a net investment hedge, then the changes in the fair value of the derivative are recognized in other comprehensive income in the same period as the change in fair value of the underlying hedged foreign investment.

Significant Accounting Policies Property and Equipment (Policies)	12 Months Ended
	Dec. 31, 2020
Accounting Policies [Abstract]
Property and Equipment	Property and Equipment Furniture, equipment, leasehold improvements and buildings are stated at cost, net of accumulated depreciation. Furniture and equipment are depreciated generally using the straight-line method over the estimated useful lives of the related assets, which range from 3 to 7 years for furniture and equipment, 10 to 35 years for buildings and the shorter of the useful life or the remaining lease term for leasehold improvements. Land is stated at cost and is not depreciated. We capitalize certain internal and external costs incurred to acquire or create internal use software, principally related to our enterprise resource planning (“ERP”) systems. Our ERP systems are stated at cost, net of accumulated amortization, and are amortized using the straight-line method over 10 years. All other internal use computer software are stated at cost, net of accumulated amortization and are amortized using the straight-line method over the estimated useful lives of the related assets, which range from 3 to 7 years.

Significant Accounting Policies Goodwill and Other Intangible Assets (Policies)	12 Months Ended
	Dec. 31, 2020
Accounting Policies [Abstract]
Goodwill and Other Intangible Assets	Goodwill and Other Intangible Assets We account for our business combinations using the acquisition accounting method, which requires us to determine the fair value of net assets acquired and the related goodwill and other intangible assets. Determining the fair value of assets acquired and liabilities assumed requires management's judgment and involves the use of significant estimates, including projections of future cash inflows and outflows, discount rates, asset lives and market multiples. Considering the characteristics of advertising, specialized marketing and communication services companies, our acquisitions usually do not have significant amounts of tangible assets, as the principal asset we typically acquire is creative talent. As a result, a substantial portion of the purchase price is allocated to goodwill and other intangible assets. We review goodwill as of October 1st each year and whenever events or significant changes in circumstances indicate that the carrying value may not be recoverable. We evaluate the recoverability of goodwill at a reporting unit level. We have 12 reporting units that were subject to the 2020 annual impairment testing. Our annual impairment review as of October 1, 2020 did not result in an impairment charge for any of our reporting units. Intangible assets with indefinite useful lives are not amortized but are evaluated for impairment annually or more frequently if events or changes in circumstances indicate that impairment may exist. The Company first assesses qualitative factors to determine whether it is necessary to perform a quantitative impairment test for indefinite-lived intangible assets. Impairment exists if the fair value of the indefinite-lived intangible asset is less than the carrying value. Our annual impairment review as of October 1, 2020 did not result in an impairment charge for any of our intangible assets with indefinite useful lives. For reporting units not included in the qualitative assessment, or for any reporting units identified in the qualitative assessment as "more likely than not" that the fair value is less than its carrying value, the quantitative impairment test is performed. For our annual impairment test, we compare the respective fair value of our reporting units' equity to the carrying value of their net assets. The sum of the fair values of all our reporting units is also reconciled to our current market capitalization plus an estimated control premium. Goodwill allocated to a reporting unit whose fair value is equal to or greater than its carrying value is not impaired, and no further testing is required. Should the carrying amount for a reporting unit exceed its fair value, then the quantitative impairment test is failed and impaired goodwill is written down to its fair value with a charge to expense in the period the impairment is identified. The fair value of each reporting unit for 2020 and 2019 was estimated using a combination of the income approach, which incorporates the use of the discounted cash flow method, and the market approach, which incorporates the use of earnings and revenue multiples based on market data. We review intangible assets with definite lives subject to amortization whenever events or circumstances indicate that a carrying amount of an asset may not be recoverable. Recoverability of these assets is determined by comparing the carrying value of these assets to the estimated undiscounted future cash flows expected to be generated by these asset groups. These asset groups are impaired when their carrying value exceeds their fair value. Impaired intangible assets with definite lives subject to amortization are written down to their fair value with a charge to expense in the period the impairment is identified. Intangible assets with definite lives are amortized on a straight-line basis with estimated useful lives generally between 7 and 15 years. Events or circumstances that might require impairment testing include the loss of a significant client, the identification of other impaired assets within a reporting unit, loss of key personnel, the disposition of a significant portion of a reporting unit, significant decline in stock price or a significant adverse change in business climate or regulations.

Significant Accounting Policies Foreign Currencies (Policies)	12 Months Ended
	Dec. 31, 2020
Accounting Policies [Abstract]
Foreign Currencies	Foreign Currencies The functional currency of our foreign operations is generally their respective local currency. Assets and liabilities are translated at the exchange rates in effect at the balance sheet date, and revenues and expenses are translated at the average exchange rates during the period presented. The resulting translation adjustments are recorded as a component of accumulated other comprehensive loss in the stockholders’ equity section of our Consolidated Balance Sheets. Currency transaction gains or losses primarily arising from transactions in currencies other than the functional currency are included in office and general expenses. Foreign currency transactions resulted in a pre-tax gain of $1.2 for the year ended December 31, 2020, a pre-tax loss of $5.3 for the year ended December 31, 2019 and a pre-tax gain $5.6 in for the year ended December 31, 2018. We monitor the currencies of countries in which we operate in order to determine if the country should be considered a highly inflationary environment. A currency is determined to be highly inflationary when there is cumulative inflation of approximately 100% or more over a three-year period. If this occurs the functional currency of that country is changed to our reporting currency, the U.S. Dollar, and foreign exchange gains or losses are recognized on all monetary transactions, assets and liabilities in currencies other than the U.S. Dollar until the currency is no longer considered highly inflationary.

Significant Accounting Policies Income Taxes (Policies)	12 Months Ended
Significant Accounting Policies Income Taxes (Policies)	Dec. 31, 2020
Accounting Policies [Abstract]
Income Taxes	Income Taxes The provision for income taxes includes U.S. federal, state, local and foreign taxes. Income taxes are accounted for under the liability method. Deferred tax assets and liabilities are recognized for the estimated future tax consequences of temporary differences between the financial statement carrying amounts and their respective tax bases. Deferred tax assets and liabilities are measured using enacted tax rates expected to apply to taxable income in the year in which the temporary differences are expected to be reversed. We evaluate the realizability of our deferred tax assets and establish a valuation allowance when it is “more likely than not” that all or a portion of the deferred tax assets will not be realized. We evaluate our tax positions using the “more likely than not” recognition threshold and then apply a measurement assessment to those positions that meet the recognition threshold. The factors used in assessing valuation allowances include all available evidence, such as past operating results, estimates of future taxable income and the feasibility of tax planning strategies. We have established tax reserves that we believe to be adequate in relation to the potential for additional assessments in each of the jurisdictions in which we are subject to taxation. We regularly assess the likelihood of additional tax assessments in those jurisdictions and adjust our reserves as additional information or events require.

- Definition

Disclosure of accounting policy for income taxes, which may include its accounting policies for recognizing and measuring deferred tax assets and liabilities and related valuation allowances, recognizing investment tax credits, operating loss carryforwards, tax credit carryforwards, and other carryforwards, methodologies for determining its effective income tax rate and the characterization of interest and penalties in the financial statements.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 45
-Paragraph 25
-URI http://asc.fasb.org/extlink&oid=120406818&loc=d3e32247-109318

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 20
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Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 954
-SubTopic 740
-Section 50
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-URI http://asc.fasb.org/extlink&oid=6491622&loc=d3e9504-115650

Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
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-Name Accounting Standards Codification
-Topic 235
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-Section 50
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-URI http://asc.fasb.org/extlink&oid=84158767&loc=d3e18780-107790

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
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-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 19
-URI http://asc.fasb.org/extlink&oid=84230637&loc=d3e32840-109319

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=116657188&loc=SL116659661-227067

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 9
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Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
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-Paragraph 28
-URI http://asc.fasb.org/extlink&oid=120406818&loc=d3e32280-109318

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 17
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=84230637&loc=d3e32809-109319

+ Details

Significant Accounting Policies Redeemable Noncontrolling Interests (Policies)	12 Months Ended
	Dec. 31, 2020
Accounting Policies [Abstract]
Redeemable Noncontrolling Interests	Redeemable Noncontrolling Interests Many of our acquisitions include provisions under which the noncontrolling equity owners can require us to purchase additional interests in a subsidiary at their discretion. Payments for these redeemable noncontrolling interests may be contingent on projected operating performance and satisfying other conditions specified in the related agreements. These payments are also subject to revision in accordance with the terms of the agreements. We record these redeemable noncontrolling interests in “mezzanine equity” in our Consolidated Balance Sheets. Each reporting period, redeemable noncontrolling interests are reported at their estimated redemption value, but not less than their initial fair value. Any adjustment to the redemption value above initial value prior to exercise will also impact retained earnings or additional paid-in capital (“APIC”), but will not impact net income. Adjustments as a result of currency translation will affect the redeemable noncontrolling interest balance, but do not impact retained earnings or additional paid-in capital.

Significant Accounting Policies Earnings Per Share (Policies)	12 Months Ended
	Dec. 31, 2020
Accounting Policies [Abstract]
Earnings Per Share	Earnings Per Share (“EPS”) Basic EPS available to IPG common stockholders equals net income available to IPG common stockholders divided by the weighted-average number of common shares outstanding for the applicable period. Diluted EPS equals net income available to IPG common stockholders divided by the weighted-average number of common shares outstanding, plus any additional common shares that would have been outstanding if potentially dilutive shares had been issued. Diluted EPS reflect the potential dilution that would occur if certain potentially dilutive securities were exercised. The potential issuance of common stock is assumed to occur at the beginning of the year (or at the time of issuance of the potentially dilutive instrument, if later) and the incremental shares are included using the treasury stock method. The proceeds utilized in applying the treasury stock method consist of the amount, if any, to be paid upon exercise and, as it relates to stock-based compensation, the amount of compensation cost attributed to future service not yet recognized. These proceeds are then assumed to be used to purchase common stock at the average market price of our stock during the period. The incremental shares (difference between the shares assumed to be issued and the shares assumed to be purchased), to the extent they would have been dilutive, are included in the denominator of the diluted EPS calculation. We may be required to calculate basic EPS using the two-class method as a result of our redeemable noncontrolling interests. To the extent that the redemption value increases and exceeds the then-current fair value of a redeemable noncontrolling interest, net income available to IPG common stockholders (used to calculate EPS) could be negatively impacted by that increase, subject to certain limitations. The partial or full recovery of any reductions to net income available to IPG common stockholders (used to calculate EPS) is limited to any cumulative prior-period reductions. For the years ended December 31, 2020, 2019 and 2018, there was no impact to EPS for adjustments related to our redeemable noncontrolling interests.

Significant Accounting Policies Pension and Postretirement Benefits (Policies)	12 Months Ended
	Dec. 31, 2020
Accounting Policies [Abstract]
Pension and Postretirement Benefits	Pension and Postretirement Benefits We have pension and postretirement benefit plans covering certain domestic and international employees. We use various actuarial methods and assumptions in determining our net pension and postretirement benefit costs and obligations, including the discount rate used to determine the present value of future benefits, expected long-term rate of return on plan assets and healthcare cost trend rates. The overfunded or underfunded status of our pension and postretirement benefit plans is recorded on our Consolidated Balance Sheet.

- Definition

Disclosure of accounting policy for pension and other postretirement benefit plans. This accounting policy may address (1) the types of plans sponsored by the entity, and the benefits provided by each plan (2) groups that participate in (or are covered by) each plan (3) how plan assets, liabilities and expenses are measured, including the use of any actuaries and (4) significant assumptions used by the entity to value plan assets and liabilities and how such assumptions are derived.

+ References + Details

Significant Accounting Policies Stock-Based Compensation (Policies)	12 Months Ended
	Dec. 31, 2020
Accounting Policies [Abstract]
Stock-Based Compensation	Stock-Based Compensation Compensation costs related to share-based transactions, including employee stock options, are recognized in the Consolidated Financial Statements based on fair value. Stock-based compensation expense is generally recognized ratably over the requisite service period based on the estimated grant-date fair value, net of estimated forfeitures.

Significant Accounting Policies Treasury Stock (Policies)	12 Months Ended
	Dec. 31, 2020
Treasury Stock, Shares [Abstract]
Treasury Stock [Text Block]	Treasury Stock We account for repurchased common stock under the cost method and include such treasury stock as a component of our Consolidated Statements of Stockholders' Equity. Upon retirement, we reduce common stock for the par value of the shares being retired and the excess of the cost of the shares over par value as a reduction to APIC, to the extent there is APIC in the same class of stock, and any remaining amount to retained earnings. These retired shares remain authorized but unissued.During 2020 and 2019, there was no significant treasury stock activity due to the suspension of the share repurchase program, as disclosed further in Note 7. In October 2018, we retired 8.1 shares of our treasury stock, which resulted in a reduction in common stock of $0.8, treasury stock of $176.1 and APIC of $175.3.

Revenue (Tables)

12 Months Ended

Dec. 31, 2020

Revenue from Contract with Customer [Abstract]

Revenue from External Customers by Geographic Areas [Table Text Block]


	Years ended December 31,
Total revenue:	2020		2019		2018
United States	$	5,751.5	$	6,368.7	$	5,851.0
International:
United Kingdom	742.9		871.8		881.4
Continental Europe	763.5		842.9		840.2
Asia Pacific	879.5		1,102.3		1,170.8
Latin America	349.7		431.6		389.0
Other	573.9		604.0		582.0
Total International	3,309.5		3,852.6		3,863.4
Total Consolidated	$	9,061.0	$	10,221.3	$	9,714.4


	Years ended December 31,
Net revenue:	2020		2019		2018
United States	$	5,211.4	$	5,386.1	$	4,825.0
International:
United Kingdom	664.3		727.0		711.7
Continental Europe	683.6		742.4		737.5
Asia Pacific	710.5		858.3		896.8
Latin America	323.4		389.9		350.1
Other	471.3		521.4		510.5
Total International	2,853.1		3,239.0		3,206.6
Total Consolidated	$	8,064.5	$	8,625.1	$	8,031.6


IAN	Years ended December 31,
Total revenue:	2020		2019		2018
United States	$	4,658.5	$	4,878.1	$	4,318.2
International	2,751.6		3,113.9		3,109.1
Total IAN	$	7,410.1	$	7,992.0	$	7,427.3

Net revenue:
United States	$	4,451.7	$	4,538.1	$	3,953.8
International	2,469.7		2,790.7		2,767.1
Total IAN	$	6,921.4	$	7,328.8	$	6,720.9


DXTRA	Years ended December 31,
Total revenue:	2020		2019		2018
United States	$	1,093.0	$	1,490.6	$	1,532.8
International	557.9		738.7		754.3
Total DXTRA	$	1,650.9	$	2,229.3	$	2,287.1

Net revenue:
United States	$	759.7	$	848.0	$	871.2
International	383.4		448.3		439.5
Total DXTRA	$	1,143.1	$	1,296.3	$	1,310.7

Contract with Customer, Asset and Liability [Table Text Block]

Contract Balances

The following table provides information about receivables, contract assets and contract liabilities from contracts with customers.


	December 31, 2020		December 31, 2019
Accounts receivable, net of allowance of $98.3 and $40.2, respectively	$	4,646.4	$	5,209.2
Accounts receivable, billable to clients	1,820.7		1,934.1
Contract assets	51.8		63.0
Contract liabilities (deferred revenue)	657.8		585.6

Leases (Tables)

12 Months Ended

Dec. 31, 2020

Leases [Abstract]

Lease, Cost [Table Text Block]

The following tables present information on our operating leases for the full years of 2020 and 2019.


	Years ended December 31,
	2020			2019
Operating lease cost	$	318.5		$	325.2
Short-term lease cost	10.6			13.8
Sublease income	(15.8)			(12.9)
Total lease cost	$	313.3		$	326.1

Cash paid related to operating lease liabilities	$	335.7		$	334.1
Right-of-use assets obtained in exchange for lease liabilities	$	274.4		$	422.8

	As of December 31,
	2020			2019
Weighted-average remaining lease term	Eight years			Eight years
Weighted-average discount rate	4.00		%	4.26		%

Schedule of Future Minimum Rental Payments for Operating Leases [Table Text Block]

Our future payments of our operating leases as of December 31, 2020 are listed in the table below.


Period	Net Rent
2021	$	322.9
2022	302.6
2023	241.2
2024	212.2
2025	194.7
Thereafter	735.2
Total future lease payments	2,008.8
Less: imputed interest	299.3
Present value of future lease payments	1,709.5
Less: current portion of operating leases	268.5
Non-current operating leases	$	1,441.0

Debt and Credit Agreements Schedule of Long-term Debt Instruments (Tables)

12 Months Ended

Dec. 31, 2020

Debt Disclosure [Abstract]

Schedule of Long-term Debt Instruments [Table Text Block]

A summary of the carrying amounts of our long-term debt is listed below.


	Effective Interest Rate		December 31,
			2020 1		2019 1
3.50% Senior Notes due 2020	3.89	%	$	—	$	498.5
3.75% Senior Notes due 2021 (less unamortized discount and issuance costs of $0.1 and $0.8, respectively)	3.98	%	499.1		497.9
4.00% Senior Notes due 2022 (less unamortized discount and issuance costs of $0.4 and $0.3, respectively)	4.13	%	249.3		248.7
3.75% Senior Notes due 2023 (less unamortized discount and issuance costs of $0.3 and $0.9, respectively)	4.32	%	498.8		498.2
4.20% Senior Notes due 2024 (less unamortized discount and issuance costs of $0.3 and $1.4, respectively)	4.24	%	498.3		497.8
4.65% Senior Notes due 2028 (less unamortized discount and issuance costs of $1.3 and $3.5, respectively)	4.78	%	495.2		494.6
4.75% Senior Notes due 2030 (less unamortized discount and issuance costs of $3.5 and $5.7, respectively)	4.92	%	640.8		—
5.40% Senior Notes due 2048 (less unamortized discount and issuance costs of $2.7 and $5.2, respectively)	5.48	%	492.1		491.9
Other notes payable and capitalized leases			44.7		46.3
Total long-term debt			3,418.3		3,273.9
Less: current portion			502.5		502.0
Long-term debt, excluding current portion			$	2,915.8	$	2,771.9

1See Note 13 for information on the fair value measurement of our long-term debt.

- Definition

Tabular disclosure of long-debt instruments or arrangements, including identification, terms, features, collateral requirements and other information necessary to a fair presentation. These are debt arrangements that originally required repayment more than twelve months after issuance or greater than the normal operating cycle of the entity, if longer.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22)
-URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 1A
-URI http://asc.fasb.org/extlink&oid=119993939&loc=d3e28541-108399

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 6
-URI http://asc.fasb.org/extlink&oid=109259400&loc=d3e21506-112644

Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08.(e),(f))
-URI http://asc.fasb.org/extlink&oid=120395691&loc=d3e23780-122690

Reference 5: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=119993939&loc=d3e28551-108399

Reference 6: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
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-URI http://asc.fasb.org/extlink&oid=109259400&loc=d3e21521-112644

Reference 7: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
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-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=109259400&loc=d3e21538-112644

Reference 8: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
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-Section 50
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-URI http://asc.fasb.org/extlink&oid=75038535&loc=d3e64711-112823

Reference 9: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 55
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=114775985&loc=d3e28878-108400

Reference 10: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=109259400&loc=d3e21475-112644

+ Details

Debt and Credit Agreements Schedule of Maturities of Long-term Debt (Tables)

12 Months Ended

Dec. 31, 2020

Long-term Debt, Fiscal Year Maturity [Abstract]

Schedule of Maturities of Long-term Debt [Table Text Block]

Annual maturities are scheduled as follows based on the book value as of December 31, 2020.


2021	$	502.5
2022	250.2
2023	498.9
2024	498.3
2025	0.0
Thereafter	1,668.4
Total long-term debt	$	3,418.3

Earnings Per Share Basic and Diluted Earnings Per Common Share Available to IPG Common Stockholders (Tables)

12 Months Ended

Dec. 31, 2020

Earnings Per Share [Abstract]

Basic and Diluted Earnings Per Common Share Available to IPG Common Stockholders

The following sets forth basic and diluted earnings per common share available to IPG common stockholders.


	Years ended December 31,
	2020		2019		2018
Net income available to IPG common stockholders	$	351.1	$	656.0	$	618.9

Weighted-average number of common shares outstanding - basic	389.4		386.1		383.3
Dilutive effect of stock options and restricted shares	3.8		5.1		5.7
Weighted-average number of common shares outstanding - diluted	393.2		391.2		389.0

Earnings per share available to IPG common stockholders:
Basic	$	0.90	$	1.70	$	1.61
Diluted	$	0.89	$	1.68	$	1.59

Acquisitions Cash Paid for Current and Prior Years' Acquisitions (Tables)

12 Months Ended

Dec. 31, 2020

Business Combinations [Abstract]

Schedule of Recognized Identified Assets Acquired and Liabilities Assumed

The following table summarizes the fair values of the assets acquired and liabilities assumed at the closing date:


	October 1, 2018
Cash and cash equivalents	$	13.3
Accounts receivable	112.9
Accounts receivable, billable to clients	8.3
Other current assets	28.2
Property and equipment, net	159.7
Deferred income taxes	(0.6)
Goodwill	1,110.8
Intangible assets, net	995.0
Other non-current assets	8.3
Accounts payable	(37.1)
Accrued liabilities	(46.9)
Contract liabilities	(23.2)
Other non-current liabilities	(0.8)
Net assets acquired	$	2,327.9

Finite-Lived and Indefinite-Lived Intangible Assets Acquired as Part of Business Combination

The fair values of the identifiable intangible assets acquired at the closing date are as follows:


	Fair Value		Weighted Average Amortization Period (Years)
Customer lists	$	600.0	15.0
Know-how and technology	235.0		9.0
Trade names	160.0		15.0 to indefinite
Total intangible assets	$	995.0

Business Acquisition, Pro Forma Information

The pro forma combined results of operations shown below include the business combination accounting effects resulting from the acquisition.


	(Unaudited)
	December 31,
	2018
Pro forma revenues	$	10,230.4
Pro forma net income	642.2

Cash Paid For Current And Prior Years' Acquisitions [Table Text Block]

Details of cash paid for current and prior years' acquisitions are listed below.


	Years ended December 31,
	2020		2019		2018
Cost of investment: current-year acquisitions 1	$	8.5	$	0.6	$	2,323.4
Cost of investment: prior-year acquisitions	45.9		15.8		33.9
Less: net cash acquired	(2.9)		—		(13.8)
Total cost of investment	51.5		16.4		2,343.5
Operating payments 2	2.9		9.3		19.4
Total cash paid for acquisitions 3	$	54.4	$	25.7	$	2,362.9

1The cost of investment: current-year acquisitions line significantly increased in the year ended December 31, 2018, primarily as a result of payments related to the acquisition of Acxiom.

Redeemable Noncontrolling Interest

The following table presents changes in our redeemable noncontrolling interests.


	Years ended December 31,
	2020		2019		2018
Balance at beginning of period	$	164.7	$	167.9	$	252.1
Change in related noncontrolling interests balance	(5.4)		(2.8)		(10.7)
Changes in redemption value of redeemable noncontrolling interests:
Additions	0.0		24.3		0.0
Redemptions and other	(20.6)		(24.9)		(33.7)
Redemption value adjustments 1	(45.6)		0.2		(39.8)
Balance at end of period	$	93.1	$	164.7	$	167.9

1Redemption value adjustments for the year ended December 31, 2020 were primarily attributable to the expiration of redemption provisions related to redeemable noncontrolling interests.

Supplementary Data Valuation and Qualifying Accounts - Allowance for Uncollectible Accounts (Tables)

12 Months Ended

Dec. 31, 2020

Valuation and Qualifying Accounts - Allowance for Uncollectible Accounts [Abstract]

Valuation and Qualifying Accounts - Allowance for Uncollectible Accounts Receivable

Valuation and Qualifying Accounts – Accounts Receivable, Allowance for Expected Credit Losses


	Years ended December 31,
	2020		2019		2018
Balance at beginning of period	$	40.2	$	42.5	$	42.7
Cumulative effect of accounting change 1	9.0		N/A		N/A
Charges to costs and expenses	50.5		10.1		6.5
Adjustments:
Acquisitions/(dispositions)	8.6		(0.3)		2.2
Uncollectible accounts written off	(11.2)		(11.9)		(7.1)
Recoveries	0.2		N/A		N/A
Foreign currency translation adjustments	1.0		(0.2)		(1.8)
Balance at end of period	$	98.3	$	40.2	$	42.5

Supplementary Data Property and Equipment (Tables)

12 Months Ended

Dec. 31, 2020

Property and Equipment [Abstract]

Property, Plant and Equipment [Table Text Block]

Property and Equipment


	December 31,
	2020		2019
Furniture and equipment	$	654.6	$	694.3
Leasehold improvements	554.6		634.9
Internal-use computer software	470.1		422.0
Land and buildings	144.9		143.3
Gross property and equipment	1,824.2		1,894.5
Less: accumulated depreciation and amortization	(1,133.9)		(1,116.4)
Total property and equipment, net	$	690.3	$	778.1

Supplementary Data Accrued Liabilities (Tables)

12 Months Ended

Dec. 31, 2020

Accrued Liabilities [Abstract]

Schedule of Accrued Liabilities [Table Text Block]

Accrued Liabilities

The following table presents the components of accrued liabilities.


	December 31,
	2020		2019
Salaries, benefits and related expenses	$	504.6	$	494.1
Restructuring charges	69.5		1.6
Income taxes payable	50.6		43.2
Acquisition obligations	47.9		45.7
Interest	43.6		38.8
Office and related expenses	25.5		26.9
Other	90.7		92.5
Total accrued liabilities	$	832.4	$	742.8

Supplementary Data Other Expense, Net (Tables)

12 Months Ended

Dec. 31, 2020

Other Nonoperating Income (Expense) [Abstract]

Schedule of Other Nonoperating Income (Expense) [Table Text Block]

Other Expense, Net

Results of operations include certain items that are not directly associated with our revenue-producing operations.


	Years ended December 31,
	2020		2019		2018
Net losses on sales of businesses	$	(67.0)	$	(43.4)	$	(61.9)
Other	2.6		0.5		(7.7)
Total other expense, net	$	(64.4)	$	(42.9)	$	(69.6)

Goodwill and Other Intangible Assets Changes in Carrying Value of Goodwill (Tables)

12 Months Ended

Dec. 31, 2020

Goodwill and Intangible Assets Disclosure [Abstract]

Changes in Carrying Value of Goodwill

The changes in the carrying value of goodwill for our reportable segments, IAN and DXTRA, for the years ended December 31, 2020 and 2019 are listed below.


	IAN		DXTRA		Total 1
Balance as of December 31, 2018	$	4,201.5	$	674.4	$	4,875.9
Acquisitions	2.1		0.7		2.8
Foreign currency and other	14.5		1.2		15.7
Balance as of December 31, 2019	$	4,218.1	$	676.3	$	4,894.4
Acquisitions	23.5		0.5		24.0
Foreign currency and other	22.9		4.2		27.1
Balance as of December 31, 2020	$	4,264.5	$	681.0	$	4,945.5

Goodwill and Other Intangible Assets Summary of Other Intangible Assets (Tables)

12 Months Ended

Dec. 31, 2020

Summary of Other Intangible Assets [Abstract]

Schedule of Finite-Lived Intangible Assets [Table Text Block]

The following table provides a summary of other intangible assets, which are included in our Consolidated Balance Sheets.


	December 31,
	2020						2019
	Gross Amount		Accumulated Amortization		Net Amount		Gross Amount		Accumulated Amortization		Net Amount
Customer lists	$	859.5	$	(293.3)	$	566.2	$	861.4	$	(244.6)	$	616.8
Know-how and technology	235.4		(58.9)		176.5		235.0		(32.9)		202.1
Trade names	224.4		(44.1)		180.3		226.2		(41.3)		184.9
Other	14.6		(4.0)		10.6		14.3		(3.8)		10.5
Total	$	1,333.9	$	(400.3)	$	933.6	$	1,336.9	$	(322.6)	$	1,014.3

Goodwill and Other Intangible Assets Estimated future amortization of other intangible assets (Tables)

12 Months Ended

Dec. 31, 2020

Summary of Other Intangible Assets [Abstract]

Schedule of Finite-Lived Intangible Assets, Future Amortization Expense [Table Text Block]

The estimated annual amortization expense for other intangible assets for the next five years as of December 31, 2020 is listed below.


	2021		2022		2023		2024		2025
Estimated amortization expense	$	88.3	$	83.8	$	79.0	$	77.3	$	74.5

Income Taxes Schedule of Income before Income Tax, Domestic and Foreign (Tables)

12 Months Ended

Dec. 31, 2020

Dec. 31, 2019

Income Tax Disclosure [Abstract]

Schedule of Income before Income Tax, Domestic and Foreign

The components of income before income taxes are listed below.


	Years ended December 31,
	2020		2019		2018
Domestic	$	279.9	$	557.4	$	474.0
Foreign	81.4		320.9		364.0
Total	$	361.3	$	878.3	$	838.0

Restructuring and Related Costs [Table Text Block]

Restructuring Charges


	Years ended December 31,
	2020		2019		2018
Severance and termination costs	$	140.4	$	22.0	$	0.0
Lease restructuring costs	256.0		11.9		0.0
Other restructuring costs	17.4		0.0		0.0
Total restructuring charges	$	413.8	$	33.9	$	0.0

Income Taxes Schedule of Components of Provision for Income Taxes (Tables)

12 Months Ended

Dec. 31, 2019

Income Tax Disclosure [Abstract]

Schedule of Components of Income Tax Expense (Benefit) [Table Text Block]

The provision for income taxes is listed below.


	Years ended December 31,
	2020		2019		2018
U.S. federal income taxes (including foreign withholding taxes):
Current	$	(52.6)	$	92.2	$	38.1
Deferred	(12.0)		9.5		29.9
	$	(64.6)	$	101.7	$	68.0
State and local income taxes:
Current	$	(3.7)	$	10.7	$	25.1
Deferred	0.5		8.7		3.4
	$	(3.2)	$	19.4	$	28.5
Foreign income taxes:
Current	$	110.7	$	92.2	$	121.9
Deferred	(34.9)		(8.5)		(19.2)
	$	75.8	$	83.7	$	102.7
Total	$	8.0	$	204.8	$	199.2

Income Taxes Schedule of Effective Income Tax Rate Reconciliation (Tables)

12 Months Ended

Dec. 31, 2019

Income Tax Disclosure [Abstract]

Schedule of Effective Income Tax Rate Reconciliation [Table Text Block]

A reconciliation of the effective income tax rate as reflected in our Consolidated Statements of Operations to the U.S. federal statutory income tax rate is listed below.


	Years ended December 31,
	2020			2019			2018
U.S. federal statutory income tax rate	21.0		%	21.0		%	21.0		%

Income tax provision at U.S. federal statutory rate	$	75.9		$	184.5		$	176.0
State and local income taxes, net of U.S. federal income tax benefit	9.4			14.0			23.8
Impact of foreign operations, including withholding taxes	49.9			34.2			50.7
U.S. tax incentives	(23.6)			(21.4)			(17.5)
Change in net valuation allowance 1	(1.3)			(26.3)			(16.9)
Divestitures	8.6			9.6			11.7
U.S. federal tax credits	(1.7)			0.4			(48.1)
Increase in unrecognized tax benefits	30.8			14.1			8.4
Net impact of the Tax Act	0.0			0.0			13.4
Settlement of income tax audit	(136.2)			0.0			0.0
Other	(3.8)			(4.3)			(2.3)
Provision for income taxes	$	8.0		$	204.8		$	199.2

Effective income tax rate on operations	2.2		%	23.3		%	23.8		%

1Reflects changes in valuation allowances that impacted the effective income tax rate for each year presented.

Income Taxes Schedule of Deferred Tax Assets and Liabilities (Tables)

12 Months Ended

Dec. 31, 2020

Income Tax Disclosure [Abstract]

Schedule of Deferred Tax Assets and Liabilities [Table Text Block]

The components of deferred tax assets and liabilities are listed below.


	December 31,
	2020		2019
Postretirement/post-employment benefits	$	16.6	$	16.7
Deferred compensation	106.5		99.5
Pension costs	27.9		23.7
Interest	42.9		45.5
Accruals and reserves	23.9		19.4
Allowance for credit losses	19.7		6.5
Operating lease liabilities	350.4		361.4
Tax loss/tax credit carry forwards	343.0		297.1
Other	83.6		44.8
Deferred tax assets	1,014.5		914.6
Valuation allowance for deferred tax assets	(197.1)		(164.2)
Net deferred tax assets	$	817.4	$	750.4

Basis differences in fixed assets	$	(86.3)	$	(75.3)
Basis differences in intangible assets	(340.0)		(321.0)
Operating lease right-of-use assets	(285.8)		(335.2)
Prepaid expenses	(7.3)		(6.7)
Deferred revenue	(11.6)		(21.7)
Unremitted foreign earnings	(9.3)		(1.3)
Deferred tax liabilities	(740.3)		(761.2)

Total net deferred tax assets (liabilities) 1	$	77.1	$	(10.8)

Income Taxes Summary of Valuation Allowance (Tables)

12 Months Ended

Dec. 31, 2020

Income Tax Disclosure [Abstract]

Summary of Valuation Allowance [Table Text Block]

The change in the valuation allowance is listed below.


	Years ended December 31,
	2020		2019		2018
Balance at beginning of period	$	164.2	$	211.0	$	243.0
Charged (reversed ) to costs and expenses	17.3		(24.9)		(28.0)
Charged (reversed) to gross tax assets and other accounts 1	9.9		(19.8)		5.1
Foreign currency translation	5.7		(2.1)		(9.1)
Balance at end of period	$	197.1	$	164.2	$	211.0

Income Taxes Schedule of Unrecognized Tax Benefits Activity (Tables)

12 Months Ended

Dec. 31, 2020

Income Tax Disclosure [Abstract]

Schedule of Unrecognized Tax Benefits Activity [Table Text Block]

The table below summarizes the activity related to our unrecognized tax benefits.


	Years ended December 31,
	2020		2019		2018
Balance at beginning of period	$	345.3	$	335.4	$	271.9
Increases as a result of tax positions taken during a prior year	18.1		22.7		65.9
Decreases as a result of tax positions taken during a prior year	(165.7)		(25.8)		(10.8)
Settlements with taxing authorities	(6.2)		(8.1)		(6.5)
Lapse of statutes of limitation	(0.7)		(0.6)		(1.7)
Increases as a result of tax positions taken during the current year	26.8		21.7		16.6
Balance at end of period	$	217.6	$	345.3	$	335.4

Accumulated Other Comprehensive Loss, Net of Tax Schedule of Accumulated Other Comprehensive Income (Loss) (Tables)

12 Months Ended

Dec. 31, 2020

Accumulated Other Comprehensive Loss [Abstract]

Schedule of Accumulated Other Comprehensive Income (Loss)

The following table presents the changes in accumulated other comprehensive loss, net of tax, by component.


	Foreign Currency Translation Adjustments		Derivative Instruments		Defined Benefit Pension and Other Postretirement Plans		Total
Balance as of December 31, 2018	$	(716.4)	$	(5.3)	$	(219.4)	$	(941.1)
Other comprehensive income (loss) before reclassifications	12.0		0.0		(14.7)		(2.7)
Amount reclassified from accumulated other comprehensive loss, net of tax	6.7		1.8		5.3		13.8
Balance as of December 31, 2019	$	(697.7)	$	(3.5)	$	(228.8)	$	(930.0)
Other comprehensive income (loss) before reclassifications	40.1		8.5		(26.3)		22.3
Amount reclassified from accumulated other comprehensive loss, net of tax	20.0		1.8		5.7		27.5
Balance as of December 31, 2020	$	(637.6)	$	6.8	$	(249.4)	$	(880.2)

Accumulated Other Comprehensive Loss, Net of Tax Reclassification out of Accumulated Other Comprehensive Income (Tables)

12 Months Ended

Dec. 31, 2020

Accumulated Other Comprehensive Loss [Abstract]

Reclassification out of Accumulated Other Comprehensive Income [Table Text Block]

Amounts reclassified from accumulated other comprehensive loss, net of tax, for the years ended December 31, 2020, 2019 and 2018 are as follows:


	Years ended December 31,						Affected Line Item in the Consolidated Statements of Operations
	2020		2019		2018
Foreign currency translation adjustments 1	$	20.0	$	6.7	$	15.7	Other expense, net
Losses on derivative instruments	2.4		2.3		2.2		Interest expense
Amortization of defined benefit pension and postretirement plans items	7.3		6.7		6.5		Other expense, net
Tax effect	(2.2)		(1.9)		(2.3)		Provision for income taxes
Total amount reclassified from accumulated other comprehensive loss, net of tax	$	27.5	$	13.8	$	22.1

1These foreign currency translation adjustments are primarily a result of the sales of businesses.

Restructuring Charges (Tables)

12 Months Ended

Dec. 31, 2020

Restructuring Charges [Abstract]

Restructuring and Related Costs [Table Text Block]

Restructuring Charges


	Years ended December 31,
	2020		2019		2018
Severance and termination costs	$	140.4	$	22.0	$	0.0
Lease restructuring costs	256.0		11.9		0.0
Other restructuring costs	17.4		0.0		0.0
Total restructuring charges	$	413.8	$	33.9	$	0.0

Schedule of Restructuring activities related to the 2020 Plan [Table Text Block]

A summary of the restructuring activities related to the 2020 Plan is as follows:


	2020 Plan
	Restructuring Expense		Non-Cash Items		Cash Payments		Liability at December 31, 2020
Severance and termination costs	$	140.4	$	4.5	$	61.3	$	74.6
Lease impairment costs	256.0		256.0		0.0		0.0
Other	17.4		5.1		12.3		0.0
Total	$	413.8	$	265.6	$	73.6	$	74.6

Incentive Compensation Plans Schedule of Stock-based Compensation Expense (Tables)

12 Months Ended

Dec. 31, 2020

Share-based Payment Arrangement, Additional Disclosure [Abstract]

Schedule of Stock-based Compensation Expense

The amounts of stock-based compensation expense as reflected in salaries and related expenses in our Consolidated Statements of Operations, and the related tax benefit, are listed below.


	Years ended December 31,
	2020		2019		2018
Stock-settled awards	$	38.4	$	33.5	$	24.7
Cash-settled awards	1.0		0.8		0.6
Performance-based awards	28.6		46.7		57.5
Employee stock purchase plan	1.4		1.1		0.9
Other 1	1.7		0.6		0.9
Stock-based compensation expense	$	71.1	$	82.7	$	84.6
Tax benefit	$	17.3	$	20.0	$	20.4

1Represents charges recorded for severance expense related to stock-based compensation awards.

Incentive Compensation Plans Schedule of Stock Options Activity (Tables)

12 Months Ended

Dec. 31, 2020

Summary of Stock Options Assumptions [Abstract]

Share-based Payment Arrangement, Option, Activity [Table Text Block]

The following table summarizes our stock option activity during 2020.


	Options	Weighted- Average Exercise Price (per option)		Weighted- Average Remaining Contractual Term (in years)	Aggregate Intrinsic Value
Stock options outstanding as of January 1, 2020	1.2	$	12.26
Exercised	(0.6)	$	11.70
Stock options outstanding as of December 31, 2020	0.6	$	12.75	2.2	$	6.8

Incentive Compensation Plans Stock-based Compensation, Grants in Period Weighted Average (Tables)

12 Months Ended

Dec. 31, 2020

Summary of Stock Options Assumptions [Abstract]

Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Weighted Average Grant Date Fair Value [Table Text Block]

Stock-based compensation awards expected to be settled in cash have been classified as liabilities in our Consolidated Balance Sheets as of December 31, 2020 and 2019.


	Years ended December 31,
	2020		2019		2018
Stock-Settled Awards:
Awards granted	2.3		2.5		2.1
Weighted-average grant-date fair value (per award)	$	20.70	$	22.78	$	23.60
Total fair value of vested awards distributed	$	17.3	$	15.2	$	24.2
Cash-Settled Awards:
Awards granted	0.0		0.0		0.1
Weighted-average grant-date fair value (per award)	$	21.02	$	22.83	$	23.62
Total fair value of vested awards distributed	$	0.3	$	0.9	$	0.8
Performance-Based Awards:
Awards granted	2.4		2.1		2.9
Weighted-average grant-date fair value (per award)	$	18.67	$	20.16	$	21.13
Total fair value of vested awards distributed	$	53.3	$	64.9	$	87.2

Incentive Compensation Plans Schedule of Nonvested Stock Activity (Tables)

12 Months Ended

Dec. 31, 2020

Summary of Stock Options Assumptions [Abstract]

Schedule of Nonvested Share Activity [Table Text Block]


	Stock-Settled Awards				Cash-Settled Awards				Performance-Based Awards
	Awards		Weighted- Average Grant-Date Fair Value (per award)		Awards		Weighted- Average Grant-Date Fair Value (per award)		Awards		Weighted- Average Grant-Date Fair Value (per award)
Non-vested as of January 1, 2020	4.7		$	23.21	0.1		$	23.20	5.6		$	21.36
Granted	2.3		20.70		0.0		21.02		2.4		18.67
Vested	(0.9)		23.71		0.0		22.12		(2.6)		22.18
Forfeited	(0.4)		22.55		0.0		23.14		(0.6)		21.12
Non-vested as of December 31, 2020	5.7		$	22.18	0.1		$	22.40	4.8		$	19.61
Total unrecognized compensation expense remaining	$	48.5			$	1.1			$	33.9
Weighted-average years expected to be recognized over	1.2				1.1				1.8

Fair Value Measurements Fair Value of Assets and Liabilities Measured on a Recurring Basis (Tables)

12 Months Ended

Dec. 31, 2020

Fair Value Disclosures [Abstract]

Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis [Table Text Block]


	December 31, 2020								Balance Sheet Classification
	Level 1		Level 2		Level 3		Total
Assets
Cash equivalents 1	$	1,507.4	$	0.0	$	0.0	$	1,507.4	Cash and cash equivalents

Liabilities
Contingent acquisition obligations 2	$	0.0	$	0.0	$	95.5	$	95.5	Accrued liabilities and Other non-current liabilities

	December 31, 2019								Balance Sheet Classification
	Level 1		Level 2		Level 3		Total
Assets
Cash equivalents 1	$	786.0	$	0.0	$	0.0	$	786.0	Cash and cash equivalents

Liabilities
Contingent acquisition obligations 2	$	0.0	$	0.0	$	114.1	$	114.1	Accrued liabilities and Other non-current liabilities

Fair Value Measurements Assets and Liabilities Measured at Fair Value on a Nonrecurring (Tables)

12 Months Ended

Dec. 31, 2020

Assets and Liabilities Measured at Fair Value on Recurring Basis [Abstract]

Fair Value Measurements, Nonrecurring [Table Text Block]


	December 31, 2020
	Level 1		Level 2		Level 3		Total
Total long-term debt	$	0.0	$	3,951.1	$	43.9	$	3,995.0

Schedule of Defined Benefit Plans Disclosures (Tables)

12 Months Ended

Dec. 31, 2020

Retirement Benefits [Abstract]

Schedule of Defined Benefit Plans Disclosures

Pension and Postretirement Benefit Obligation


	Domestic Pension Plan				Foreign Pension Plans				Domestic Postretirement Benefit Plan

	2020		2019		2020		2019		2020		2019
Benefit Obligation
Projected benefit obligation as of January 1	$	116.9	$	115.4	$	541.2	$	496.0	$	27.2	$	27.7
Service cost	0.0		0.0		4.9		4.8		0.0		0.0
Interest cost	3.7		4.8		9.4		12.4		0.8		1.2
Benefits paid	(10.1)		(9.2)		(22.9)		(27.8)		(5.2)		(5.4)
Plan participant contributions	0.0		0.0		0.0		0.0		2.1		2.0
Actuarial losses	6.3		5.9		54.3		42.7		0.9		1.7
Settlements and curtailments	0.0		0.0		(4.9)		(0.7)		0.0		0.0
Foreign currency effect	0.0		0.0		23.3		13.8		0.0		0.0
Other	0.0		0.0		0.6		0.0		0.0		0.0

Projected benefit obligation as of December 31	$	116.8	$	116.9	$	605.9	$	541.2	$	25.8	$	27.2

Fair Value of Plan Assets
Fair value of plan assets as of January 1	$	99.1	$	89.8	$	409.5	$	363.9	$	0.0	$	0.0
Actual return on plan assets	10.6		16.1		45.7		42.0		0.0		0.0
Employer contributions	1.3		2.4		18.4		18.0		3.1		3.4
Plan participant contributions	0.0		0.0		0.0		0.0		2.1		2.0
Benefits paid	(10.1)		(9.2)		(22.9)		(27.8)		(5.2)		(5.4)
Settlements	0.0		0.0		(4.9)		0.0		0.0		0.0
Foreign currency effect	0.0		0.0		15.8		13.4		0.0		0.0

Fair value of plan assets as of December 31	$	100.9	$	99.1	$	461.6	$	409.5	$	0.0	$	0.0

Funded status of the plans at December 31	$	(15.9)	$	(17.8)	$	(144.3)	$	(131.7)	$	(25.8)	$	(27.2)


	Domestic Pension Plan				Foreign Pension Plans				Domestic Postretirement Benefit Plan
December 31,	2020		2019		2020		2019		2020		2019
Amounts recognized in Consolidated Balance Sheets
Non-current asset	$	0.0	$	0.0	$	10.9	$	10.1	$	0.0	$	0.0
Current liability	0.0		0.0		(7.4)		(5.8)		(2.5)		(2.7)
Non-current liability	(15.9)		(17.8)		(147.8)		(136.0)		(23.3)		(24.5)

Net liability recognized	$	(15.9)	$	(17.8)	$	(144.3)	$	(131.7)	$	(25.8)	$	(27.2)

Accumulated benefit obligation	$	116.8	$	116.9	$	603.3	$	538.6

Amounts recognized in Accumulated Other Comprehensive Loss, net
Net actuarial loss	$	53.9	$	54.2	$	213.3	$	183.2	$	5.4	$	4.7
Prior service cost (credit)	0.0		0.0		1.1		1.1		0.0		(0.1)

Total amount recognized	$	53.9	$	54.2	$	214.4	$	184.3	$	5.4	$	4.6


	Domestic Pension Plan				Foreign Pension Plans
December 31,	2020		2019		2020		2019
Pension plans with an accumulated benefit obligation and projected benefit obligation in excess of plan assets
Aggregate projected benefit obligation	$	116.8	$	116.9	$	600.8	$	534.6
Aggregate accumulated benefit obligation	116.8		116.9		600.1		533.5
Aggregate fair value of plan assets	100.9		99.1		445.6		392.7

Employee Benefits Schedule of Net Benefit Costs (Tables)

12 Months Ended

Dec. 31, 2020

Retirement Benefits [Abstract]

Schedule of Net Benefit Costs [Table Text Block]

Net Periodic Cost

The components of net periodic benefit cost and key assumptions are listed below.


	Domestic Pension Plan						Foreign Pension Plans						Domestic Postretirement Benefit Plan
Years ended December 31,	2020		2019		2018		2020		2019		2018		2020		2019		2018
Service cost	$	0.0	$	0.0	$	0.0	$	4.9	$	4.8	$	5.4	$	0.0	$	0.0	$	0.0
Interest cost	3.7		4.8		4.5		9.4		12.4		13.1		0.8		1.2		1.1
Expected return on plan assets	(5.7)		(5.9)		(6.6)		(18.8)		(17.4)		(18.8)		0.0		0.0		0.0
Settlement and curtailment	0.0		0.0		0.0		(0.1)		0.0		(1.0)		0.0		0.0		0.0
Amortization of:
Prior service cost (credit)	0.0		0.0		0.0		0.1		0.1		0.1		0.0		(0.2)		(0.2)
Net actuarial losses	1.7		1.9		1.6		5.4		4.8		5.9		0.2		0.1		0.1
Net periodic cost	$	(0.3)	$	0.8	$	(0.5)	$	0.9	$	4.7	$	4.7	$	1.0	$	1.1	$	1.0

Assumptions


	Domestic Pension Plan						Foreign Pension Plans						Domestic Postretirement Benefit Plan
Years ended December 31,	2020		2019		2018		2020		2019		2018		2020		2019		2018

Net periodic cost
Discount rate	3.35	%	4.35	%	3.70	%	1.84	%	2.61	%	2.36	%	3.25	%	4.30	%	3.65	%
Rate of compensation increase	N/A		N/A		N/A		2.51	%	2.58	%	2.37	%	N/A		N/A		N/A
Expected return on plan assets	6.00	%	7.00	%	7.00	%	4.70	%	4.76	%	4.70	%	N/A		N/A		N/A
Interest crediting rates	5.10	%	5.10	%	5.10	%	1.37	%	1.44	%	1.31	%	N/A		N/A		N/A

Benefit obligation
Discount rate	2.60	%	3.35	%	4.35	%	1.35	%	1.84	%	2.61	%	2.50	%	3.25	%	4.30	%
Rate of compensation increase	N/A		N/A		N/A		2.47	%	2.51	%	2.58	%	N/A		N/A		N/A
Interest crediting rates	5.10	%	5.10	%	5.10	%	1.50	%	1.37	%	1.44	%	N/A		N/A		N/A

Health care cost trend rate assumed for next year
Initial rate (weighted-average)													6.75	%	7.00	%	6.25	%
Year ultimate rate is reached													2028		2028		2024
Ultimate rate													5.00	%	5.00	%	5.00	%

Employee Benefits Fair Value of Pension Plan Assets (Tables)

12 Months Ended

Dec. 31, 2020

Retirement Benefits [Abstract]

Fair Value of Pension Plan Assets [Table Text Block]


	December 31, 2020								December 31, 2019
Plan assets subject to fair value hierarchy	Level 1		Level 2		Level 3		Total		Level 1		Level 2		Level 3		Total
Registered investment companies	$	19.3	$	0.0	$	0.0	$	19.3	$	18.0	$	0.0	$	0.0	$	18.0
Limited partnerships	0.0		0.0		25.9		25.9		0.0		0.0		25.6		25.6
Fixed income securities	22.7		0.0		0.0		22.7		19.6		0.0		0.0		19.6
Insurance contracts	0.0		3.6		0.0		3.6		0.0		5.5		0.0		5.5
Other	28.9		0.0		0.0		28.9		27.8		0.0		0.0		27.8
Total plan assets, subject to leveling	$	70.9	$	3.6	$	25.9	$	100.4	$	65.4	$	5.5	$	25.6	$	96.5
Plan assets measured at net asset value
Other investments measured at net asset value 1							462.1								412.1
Total plan assets							$	562.5							$	508.6

Employee Benefits Schedule of Effect of Significant Unobservable Inputs, Changes in Plan Assets (Tables)

12 Months Ended

Dec. 31, 2020

Retirement Benefits [Abstract]

Schedule of Effect of Significant Unobservable Inputs, Changes in Plan Assets [Table Text Block]

The following table presents additional information about our significant foreign pension plan assets for which we utilize Level 3 inputs to determine fair value.


	Years ended December 31,
Plan assets subject to fair value hierarchy, Level 3	2020		2019

Balance at beginning of period	$	25.6	$	25.6
Actual return on plan assets	0.3		0.0


Balance at end of period	$	25.9	$	25.6

Employee Benefits Schedule of Allocation of Plan Assets (Tables)

12 Months Ended

Dec. 31, 2020

Retirement Benefits [Abstract]

Schedule of Allocation of Plan Assets [Table Text Block]

As of December 31, 2020, the weighted-average target and actual asset allocations relating to our domestic and foreign pension plans' assets are listed below.


			December 31,
Asset Class	2021 Target Allocation		2020		2019
Alternative investments 1	23	%	24	%	25	%
Equity securities	27	%	27	%	25	%
Fixed income securities	19	%	18	%	19	%
Liability driven investments 2	15	%	15	%	14	%
Real estate	9	%	9	%	9	%
Other	7	%	7	%	8	%
Total	100	%	100	%	100	%

1Alternative investments have the flexibility to dynamically invest across a broad range of asset classes including bonds, equity, cash, property and commodities.

2Liability driven investment strategies use government bonds as well as derivative instruments to hedge a portion of the impact of interest rates and inflation movements on the long-term liabilities.

Employee Benefits Schedule of Estimated Future Benefit Payments (Tables)

12 Months Ended

Dec. 31, 2020

Retirement Benefits [Abstract]

Schedule of Expected Benefit Payments [Table Text Block]

The estimated future benefit payments expected to be paid are presented below.


Years	Domestic Pension Plan		Foreign Pension Plans		Domestic Postretirement Benefit Plan
2021	$	10.2	$	25.0	$	2.5
2022	8		22.9		2.3
2023	7.5		24.0		2.1
2024	7.5		25.2		2.0
2025	7.4		25.9		1.8
2026 - 2030	34.2		129.5		8.0

Segment Information Schedule of Segment Reporting Information, by Segment (Tables)

12 Months Ended

Dec. 31, 2020

Segment Reporting [Abstract]

Schedule of Segment Reporting Information, by Segment

Summarized financial information concerning our reportable segments is shown in the following tables.


	Years ended December 31,
	2020		2019		2018
Total Revenue:
IAN	$	7,410.1	$	7,992.0	$	7,427.3
DXTRA	1,650.9		2,229.3		2,287.1
Total	$	9,061.0	$	10,221.3	$	9,714.4

Net revenue:
IAN	$	6,921.4	$	7,328.8	$	6,720.9
DXTRA	1,143.1		1,296.3		1,310.7
Total	$	8,064.5	$	8,625.1	$	8,031.6

Segment EBITA 1:
IAN	$	699.1	$	1,115.7	$	1,038.8
DXTRA	56.5		158.1		183.6
Corporate and other	(81.3)		(101.8)		(176.0)
Total	$	674.3	$	1,172.0	$	1,046.4

Amortization of acquired intangibles:
IAN	$	81.5	$	81.6	$	32.2
DXTRA	4.4		4.4		5.4
Corporate and other	0.0		0.0		0.0
Total	$	85.9	$	86.0	$	37.6

Depreciation and amortization 2:
IAN	$	178.9	$	164.6	$	136.0
DXTRA	20.4		20.6		19.8
Corporate and other	5.4		7.3		9.5
Total	$	204.7	$	192.5	$	165.3

Capital expenditures:
IAN	$	132.0	$	161.8	$	143.7
DXTRA	8.4		13.3		13.2
Corporate and other	27.1		23.4		20.2
Total	$	167.5	$	198.5	$	177.1

2 Excludes amortization of acquired intangibles.


	December 31,
	2020		2019
Total assets:
IAN	$	14,784.5	$	15,155.2
DXTRA	1,549.2		1,725.5
Corporate and other	1,709.0		871.2
Total	$	18,042.7	$	17,751.9

The following table presents the reconciliation of segment EBITA to Income before income taxes.


	Years ended December 31,
	2020		2019		2018
IAN EBITA	$	699.1	$	1,115.7	$	1,038.8
DXTRA EBITA	56.5		158.1		183.6
Corporate and other EBITA	(81.3)		(101.8)		(176.0)
Less: consolidated amortization of acquired intangibles	85.9		86.0		37.6
Operating income	588.4		1,086.0		1,008.8
Total (expenses) and other income	(227.1)		(207.7)		(170.8)
Income before income taxes	$	361.3	$	878.3	$	838.0

Segment Information Schedule of Revenue from External Customers and Long-Lived Assets, by Geographical Areas (Tables)

12 Months Ended

Dec. 31, 2020

Segment Reporting [Abstract]

Schedule of Revenue from External Customers and Long-Lived Assets, by Geographical Areas [Table Text Block]

Long-lived assets, including operating lease right-of-use assets and excluding intangible assets, are presented by major geographic area in the following table.


	Long-Lived Assets
	December 31,
	2020		2019
Domestic	$	1,801.4	$	2,080.4
International:
United Kingdom	216.6		167.6
Continental Europe	117.5		149.7
Asia Pacific	183.1		240.9
Latin America	58.9		74.8
Other	116.5		130.4
Total International	692.6		763.4
Total Consolidated	$	2,494.0	$	2,843.8

Property and equipment are allocated based upon physical location. Other assets and investments are allocated based on the location of the related operations.

Commitments and Contingencies Schedule of Contingent Acquisition Obligations (Tables)

12 Months Ended

Dec. 31, 2020

Commitments and Contingencies Disclosure [Abstract]

Schedule of Business Acquisitions by Acquisition, Contingent Consideration [Table Text Block]

Contingent Acquisition Obligations

The following table details the estimated future contingent acquisition obligations payable in cash as of December 31, 2020.


	2021		2022		2023		2024		2025		Thereafter		Total
Deferred acquisition payments	$	47.9	$	10.9	$	7.0	$	8.4	$	0.0	$	2.9	$	77.1
Redeemable noncontrolling interests and call options with affiliates 1	17.2		23.3		26.8		1.5		0.7		0.0		69.5
Total contingent acquisition payments	$	65.1	$	34.2	$	33.8	$	9.9	$	0.7	$	2.9	$	146.6

Summary of Significant Accounting Policies (Details) shares in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($) shares	Jan. 01, 2019 USD ($)
Operating Lease, Right-of-Use Asset	$ 1,379.3	$ 1,574.4		$ 1,421.1
Operating Lease, Liability	1,709.5			$ 1,544.4
Revenue, remaining performance obligation, amount	$ 654.0
Retirement of treasury stock, amount			$ 0.0
ERP Systems, Useful Life	10
Minimum Remaining Lease Term	1 year
Maximum Remaining Lease Term	19 years
Leasehold Improvements, Useful Life	the shorter of the useful life or the remaining lease term
Number of Reporting Units for Purposes of Annual Goodwill Impairment Test	12
Foreign Currency Transaction pre-tax Gain (Loss)	$ (1.2)	$ 5.3	$ (5.6)
Minimum
Furniture and Equipment, Useful Life	3 years
Buildings, Useful Life	10 years
Other Internal Use Software, Useful Life	3
Identifiable Intangible Assets, Useful Life	7 years
Maximum
Furniture and Equipment, Useful Life	7 years
Buildings, Useful Life	35 years
Other Internal Use Software, Useful Life	7
Identifiable Intangible Assets, Useful Life	15 years
Common Stock [Member]
Retirement of treasury stock, shares \| shares			8.1
Retirement of treasury stock, amount			$ (0.8)
Treasury Stock [Member]
Retirement of treasury stock, amount			176.1
Additional Paid-in Capital [Member]
Retirement of treasury stock, amount			$ (175.3)

Revenue Major Geographical Area (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Net revenue	$ 2,284.4	$ 1,954.6	$ 1,853.4	$ 1,972.1	$ 2,433.0	$ 2,061.4	$ 2,125.9	$ 2,004.8	$ 8,064.5	$ 8,625.1	$ 8,031.6
Total revenue	$ 2,550.0	$ 2,125.5	$ 2,025.7	$ 2,359.8	$ 2,901.8	$ 2,438.1	$ 2,520.2	$ 2,361.2	9,061.0	10,221.3	9,714.4
United States
Net revenue									5,211.4	5,386.1	4,825.0
Total revenue									5,751.5	6,368.7	5,851.0
Total International
Net revenue									2,853.1	3,239.0	3,206.6
Total revenue									3,309.5	3,852.6	3,863.4
United Kingdom
Net revenue									664.3	727.0	711.7
Total revenue									742.9	871.8	881.4
Continental Europe
Net revenue									683.6	742.4	737.5
Total revenue									763.5	842.9	840.2
Asia Pacific
Net revenue									710.5	858.3	896.8
Total revenue									879.5	1,102.3	1,170.8
Latin America
Net revenue									323.4	389.9	350.1
Total revenue									349.7	431.6	389.0
Other
Net revenue									471.3	521.4	510.5
Total revenue									573.9	604.0	582.0
IAN
Net revenue									6,921.4	7,328.8	6,720.9
Total revenue									7,410.1	7,992.0	7,427.3
IAN \| United States
Net revenue									4,451.7	4,538.1	3,953.8
Total revenue									4,658.5	4,878.1	4,318.2
IAN \| Total International
Net revenue									2,469.7	2,790.7	2,767.1
Total revenue									2,751.6	3,113.9	3,109.1
DXTRA
Net revenue									1,143.1	1,296.3	1,310.7
Total revenue									1,650.9	2,229.3	2,287.1
DXTRA \| United States
Net revenue									759.7	848.0	871.2
Total revenue									1,093.0	1,490.6	1,532.8
DXTRA \| Total International
Net revenue									383.4	448.3	439.5
Total revenue									$ 557.9	$ 738.7	$ 754.3

Leases (Details) - USD ($) $ in Millions	12 Months Ended
Leases (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019	Jan. 01, 2019
Operating Lease, Liability, Leases Not Commenced	$ 52.0
Lessee, Operating Lease, Liability, Payments, Due Next Twelve Months	322.9
Operating Lease, Expense	$ 318.5	$ 325.2
Minimum Remaining Lease Term	1 year
Maximum Remaining Lease Term	19 years
Short-term Lease, Cost	$ 10.6	13.8
Sublease Income	(15.8)	(12.9)
Lease, Cost	313.3	326.1
Operating Lease, Payments	335.7	334.1
Right-of-Use Asset Obtained in Exchange for Operating Lease Liability	$ 274.4	$ 422.8
Operating Lease, Weighted Average Remaining Lease Term	8 years	8 years
Operating Lease, Weighted Average Discount Rate, Percent	4.00%	4.26%
Lessee, Operating Lease, Liability, Payments, Due Year Two	$ 302.6
Lessee, Operating Lease, Liability, Payments, Due Year Three	241.2
Lessee, Operating Lease, Liability, Payments, Due Year Four	212.2
Lessee, Operating Lease, Liability, Payments, Due Year Five	194.7
Lessee, Operating Lease, Liability, Payments, Due after Year Five	735.2
Lessee, Operating Lease, Liability, Payments, Due	2,008.8
Lessee, Operating Lease, Liability, Undiscounted Excess Amount	299.3
Operating Lease, Liability	1,709.5		$ 1,544.4
Operating Lease, Liability, Current	268.5	$ 267.2
Operating Lease, Liability, Noncurrent	$ 1,441.0	$ 1,429.6
Minimum Lease Term for Leases That Have Not Yet Commenced	1 year
Maximum Lease Term for Leases That Have Not Yet Commenced	10 years

Debt and Credit Agreements Long-Term Debt (Details) - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Debt Instrument [Line Items]
Long-term debt, gross	$ 3,418,300,000	$ 3,273,900,000
Long-term debt, current maturities	502,500,000	502,000,000.0
Long-term debt, excluding current maturities	2,915,800,000	2,771,900,000
Deb instrument, unamortized debt issuance costs	24,300,000	21,600,000
Long-term debt, fair value	3,995,000,000.0	3,565,500,000
3.50% Notes Due 2020
Debt Instrument [Line Items]
Senior Notes	500,000,000.0
Long-term debt, gross	$ 0	498,500,000
Interest rate, stated percentage	3.50%
Debt instrument, interest rate, effective percentage	3.89%
3.75% Notes Due 2021 (less unamortized discount and issuance costs of $0.1 and $0.8, respectively)
Debt Instrument [Line Items]
Senior Notes	$ 500,000,000.0
Long-term debt, gross	499,100,000	497,900,000
Debt instrument, unamortized discount	100,000
Deb instrument, unamortized debt issuance costs	$ 800,000
Debt instrument, maturity date	Oct. 01, 2021
Interest rate, stated percentage	3.75%
Debt instrument, interest rate, effective percentage	3.98%
4.00% Notes Due 2022 (less unamortized discount and issuance costs of $0.4 and $0.3, respectively)
Debt Instrument [Line Items]
Senior Notes	$ 250,000,000.0
Long-term debt, gross	249,300,000	248,700,000
Debt instrument, unamortized discount	400,000
Deb instrument, unamortized debt issuance costs	$ 300,000
Debt instrument, maturity date	Mar. 15, 2022
Interest rate, stated percentage	4.00%
Debt instrument, interest rate, effective percentage	4.13%
3.75% Notes Due 2023 (less unamortized discount and issuance costs of $0.3 and $0.9, respectively)
Debt Instrument [Line Items]
Senior Notes	$ 500,000,000.0
Long-term debt, gross	498,800,000	498,200,000
Debt instrument, unamortized discount	300,000
Deb instrument, unamortized debt issuance costs	$ 900,000
Debt instrument, maturity date	Feb. 15, 2023
Interest rate, stated percentage	3.75%
Debt instrument, interest rate, effective percentage	4.32%
4.20% Notes Due 2024 (less unamortized discount and issuance costs of $0.3 and $1.4, respectively)
Debt Instrument [Line Items]
Senior Notes	$ 500,000,000.0
Long-term debt, gross	498,300,000	497,800,000
Debt instrument, unamortized discount	300,000
Deb instrument, unamortized debt issuance costs	$ 1,400,000
Debt instrument, maturity date	Apr. 15, 2024
Interest rate, stated percentage	4.20%
Debt instrument, interest rate, effective percentage	4.24%
4.65% Notes Due 2028 (less unamortized discount and issuance costs of $1.3 and $3.5, respectively)
Debt Instrument [Line Items]
Senior Notes	$ 500,000,000.0
Long-term debt, gross	495,200,000	494,600,000
Debt instrument, unamortized discount	1,300,000
Deb instrument, unamortized debt issuance costs	$ 3,500,000
Debt instrument, maturity date	Oct. 01, 2028
Interest rate, stated percentage	4.65%
Debt instrument, interest rate, effective percentage	4.78%
4.75% Note Due 2030 (less unamortized discount and issuance costs of $3.5 and $5.7, respectively)
Debt Instrument [Line Items]
Senior Notes	$ 650,000,000.0
Long-term debt, gross	640,800,000	0
Debt instrument, unamortized discount	3,500,000
Deb instrument, unamortized debt issuance costs	$ 5,700,000
Debt instrument, maturity date	Mar. 30, 2030
Interest rate, stated percentage	4.75%
Debt instrument, interest rate, effective percentage	4.92%
5.40% Notes Due 2048 (less unamortized discount and issuance costs of $2.7 and $5.2, respectively)
Debt Instrument [Line Items]
Senior Notes	$ 500,000,000.0
Long-term debt, gross	492,100,000	491,900,000
Debt instrument, unamortized discount	2,700,000
Deb instrument, unamortized debt issuance costs	$ 5,200,000
Debt instrument, maturity date	Oct. 01, 2048
Interest rate, stated percentage	5.40%
Debt instrument, interest rate, effective percentage	5.48%
Other notes payable and capitalized leases
Debt Instrument [Line Items]
Long-term debt, gross	$ 44,700,000	$ 46,300,000

Debt and Credit Agreements Debt Transactions (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2018
Schedule of New Debt Issuance [Line Items]
Debt Issuance Face Amount		$ 2,000.0
3.50% Notes Due 2020
Schedule of New Debt Issuance [Line Items]
Debt Instrument, Face Amount	$ 500.0
3.75% Notes Due 2021
Schedule of New Debt Issuance [Line Items]
Debt Instrument, Face Amount	500.0
Debt instrument, unamortized discount	0.1
4.00% Notes Due 2022
Schedule of New Debt Issuance [Line Items]
Debt Instrument, Face Amount	250.0
Debt instrument, unamortized discount	0.4
3.75% Notes Due 2023
Schedule of New Debt Issuance [Line Items]
Debt Instrument, Face Amount	500.0
Debt instrument, unamortized discount	0.3
4.20% Notes Due 2024
Schedule of New Debt Issuance [Line Items]
Debt Instrument, Face Amount	500.0
Debt instrument, unamortized discount	0.3
4.65% Notes Due 2028
Schedule of New Debt Issuance [Line Items]
Debt Instrument, Face Amount	500.0
Debt instrument, unamortized discount	1.3
4.75% Note Due 2030
Schedule of New Debt Issuance [Line Items]
Debt Instrument, Face Amount	650.0
Debt instrument, unamortized discount	3.5
5.40% Notes Due 2048
Schedule of New Debt Issuance [Line Items]
Debt Instrument, Face Amount	500.0
Debt instrument, unamortized discount	2.7
Unsecured Debt 4.75% Senior Notes [Member]
Schedule of New Debt Issuance [Line Items]
Unsecured Debt	640.0
Debt instrument, unamortized discount	3.8
Debt Issuance Costs, Gross	$ 6.2

Debt and Credit Agreements Annual Maturities (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Debt Disclosure [Abstract]
Long-term debt, maturities, repayments of principal in next twelve months	$ 502.5
Long-term debt, maturities, repayments of principal in year two	250.2
Long-term debt, maturities,repayments of principal in year three	498.9
Long-term debt, maturities, repayments of principal in year four	498.3
Long-term debt, maturities, repayments of principal in year five	0.0
Long-term debt, maturities, repayments of principal after year five	1,668.4
Total long-term debt	$ 3,418.3	$ 3,273.9

Debt and Credit Agreements Credit Agreements (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Line of Credit Facility [Line Items]
Cash debt pooling arrangements, amount netted	$ 2,702.2	$ 2,274.9
Margin for base rate advances	0.125%
Margin for Eurocurrency rate advances	1.125%
Annual rate for fronting fees accrued on letters of credit	0.25%
Annual facility fee	0.125%
Leverage ratio maximum	4.25x
Debt Instrument, Fee Amount	$ 2.0
364 Day [Member]
Line of Credit Facility [Line Items]
Margin for base rate advances	0.25%
Margin for Eurocurrency rate advances	1.25%
Annual facility fee	0.25%
Line of credit facility, current borrowing capacity	$ 500.0
Line of Credit Facility, Fair Value of Amount Outstanding	0.0
Committed credit facility [Member]
Line of Credit Facility [Line Items]
Line of credit facility, maximum borrowing capacity	1,500.0
Line of credit facility, available capacity increase amount	250.0
Limits on letters of credit	50.0
Line of credit facility, amount outstanding	0.0
Letters of credit, amount outstanding	9.0	8.4
Line of credit facility, remaining borrowing capacity	1,491.0	1,491.6
Uncommitted credit facility
Line of Credit Facility [Line Items]
Line of credit facility, amount outstanding	48.0	52.4
Line of Credit Facility, Average Outstanding Amount	86.5	88.0
Line of credit facility, current borrowing capacity	$ 857.6	$ 1,056.0
Line of credit facility, weighted average interest rate, over time	3.60%	5.20%

Debt and Credit Agreements Commercial Paper (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Debt Disclosure [Abstract]
Commercial paper, current borrowing capacity	$ 1,500.0
Debt Instrument, Term	397 days
Commercial paper, amount outstanding	$ 0.0
Commercial paper, average outstanding amount	$ 105.8	$ 312.9
Commercial paper, weighted average interest rate, over time	1.50%	2.50%
Commercial paper, weighted-average maturity days outstanding, over time	twelve	thirteen days

Debt and Credit Agreements Cash Pooling (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Debt Disclosure [Abstract]
Cash debt pooling arrangements, amount netted	$ 2,702.2	$ 2,274.9

Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Earnings Per Share [Abstract]
Net Income (Loss) Attributable to Parent									$ 351.1	$ 656.0	$ 618.9
Weighted-average number of common shares outstanding, Basic									389.4	386.1	383.3
Restricted stock, stock options and other equity awards									3.8	5.1	5.7
Weighted-average number of common shares outstanding, Diluted									393.2	391.2	389.0
Basic	$ 0.29	$ 0.72	$ (0.12)	$ 0.01	$ 0.85	$ 0.43	$ 0.44	$ (0.02)	$ 0.90	$ 1.70	$ 1.61
Diluted	$ 0.28	$ 0.71	$ (0.12)	$ 0.01	$ 0.84	$ 0.42	$ 0.43	$ (0.02)	$ 0.89	$ 1.68	$ 1.59

- Definition

The amount of net income (loss) for the period per each share of common stock or unit outstanding during the reporting period.

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The amount of net income (loss) for the period available to each share of common stock or common unit outstanding during the reporting period and to each share or unit that would have been outstanding assuming the issuance of common shares or units for all dilutive potential common shares or units outstanding during the reporting period.

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Reference 20: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 260
-SubTopic 10
-Section 45
-Paragraph 60B
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=121326447&loc=SL5780133-109256

Reference 21: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 323
-SubTopic 10
-Section 50
-Paragraph 3
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=114001798&loc=d3e33918-111571

Reference 22: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 32
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e8933-108599

Reference 23: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 250
-SubTopic 10
-Section 50
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=109234566&loc=d3e22658-107794

+ Details

Acquisitions Narrative (Details) $ in Millions	12 Months Ended
Acquisitions Narrative (Details) $ in Millions	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)
Goodwill and intangible assets related to acquisitions	$ 28.0	$ 7.6	$ 2,131.0
Number of businesses acquired	4	1	5
Interest income	$ 29.5	$ 34.5	$ 21.8
IAN
Number of businesses acquired	3		2
DXTRA
Number of businesses acquired	1		3

Acquisitions Cash Paid for Acquisitions (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Cash Paid for Acquisitions [Abstract]
Cost of investment: current-year acquisitions 1	$ 8.5	$ 0.6	$ 2,323.4
Cost of investment: prior-year acquisitions	45.9	15.8	33.9
Less: net cash acquired	(2.9)	0.0	(13.8)
Total cost of investment	51.5	16.4	2,343.5
Operating payments	2.9	9.3	19.4
Total cash paid for acquisitions	54.4	25.7	2,362.9
Acquisitions, net of cash acquired	4.9	0.6	2,309.8
Payments for previous acquisition, financing cash flows	$ 46.6	$ 15.8	$ 33.7

Redeemable Noncontrolling Interests (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Redeemable Noncontrolling Interests
Balance at beginning of period	$ 164.7	$ 167.9	$ 252.1
Change in related noncontrolling interest balance	(5.4)	(2.8)	(10.7)
Changes in redemption value of redeemable noncontrolling interests:
Additions	0.0	24.3	0.0
Redemptions and other	(20.6)	(24.9)	(33.7)
Redemption value adjustments	(45.6)	0.2	(39.8)
Balance at end of period	$ 93.1	$ 164.7	$ 167.9

Acquisitions Acxiom Acquisition (Details) - USD ($) $ in Millions	3 Months Ended									12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Oct. 01, 2018
Business Acquisition [Line Items]
Business Acquisition, Pro Forma Revenue												$ 10,230.4
Finite-Lived Intangible Assets, Gross	$ 1,333.9				$ 1,336.9					$ 1,333.9	$ 1,336.9
Cash and Cash Equivalents, at Carrying Value	2,509.0				1,192.2					2,509.0	1,192.2		$ 13.3
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Assets													2,327.9
Loans Payable									$ 500.0			500.0
Debt Issuance Face Amount									2,000.0			2,000.0
Accounts receivable, net of allowance	4,646.4				5,209.2					4,646.4	5,209.2		112.9
Accounts receivable, billable to clients	1,820.7				1,934.1					1,820.7	1,934.1		8.3
Other current assets	390.7				412.4					390.7	412.4		28.2
Property, Plant and Equipment, Net	690.3				778.1					690.3	778.1		159.7
Deferred Income Taxes and Other Tax Liabilities, Noncurrent													(0.6)
Goodwill	4,945.5				4,894.4				4,875.9	4,945.5	4,894.4	4,875.9	1,110.8
Intangible Assets, Net (Excluding Goodwill)													995.0
Other non-current assets	424.4				467.9					424.4	467.9		8.3
Accounts Payable													(37.1)
Accrued Liabilities													(46.9)
Contract liabilities	(657.8)				(585.6)					(657.8)	(585.6)		(23.2)
Other non-current liabilities	(655.2)				(714.7)					(655.2)	(714.7)		(0.8)
Net revenue	2,284.4	$ 1,954.6	$ 1,853.4	$ 1,972.1	2,433.0	$ 2,061.4	$ 2,125.9	$ 2,004.8		8,064.5	8,625.1	8,031.6
Net Income (Loss) Attributable to Parent										351.1	656.0	618.9
Business Acquisition, Pro Forma Net Income (Loss)												642.2
Selling General and Administrative Expense (Acquiree)												35.0
Interest Expense (Acquiree)												3.7
Interest Income (Acquiree)												0.4
Other Nonoperating Income Expense (Acquiree)												10.3
Goodwill and intangible assets related to acquisitions	28.0				7.6				2,131.0	28.0	7.6	$ 2,131.0
Customer Lists [Member]
Business Acquisition [Line Items]
Finite-Lived Intangible Assets, Gross	859.5				861.4					859.5	$ 861.4		600.0
Finite-Lived Intangible Asset, Useful Life											15 years
know-how technology [Member]
Business Acquisition [Line Items]
Finite-Lived Intangible Assets, Gross	224.4				226.2					224.4	$ 226.2		235.0
Finite-Lived Intangible Asset, Useful Life											9 years
Trade Names [Member]
Business Acquisition [Line Items]
Finite-Lived Intangible Assets, Gross	$ 235.4				$ 235.0					$ 235.4	$ 235.0		995.0
Indefinite-Lived Trade Names													$ 160.0
Acxiom [Member]
Business Acquisition [Line Items]
Net revenue									181.7
Net Income (Loss) Attributable to Parent									$ 20.4

Valuation and Qualifying Accounts - Allowance for Uncollectible Accounts Receivable (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at beginning of period	$ 40.2	$ 42.5	$ 42.7
Charges to costs and expenses	50.5	10.1	6.5
Acquisitions/(dispositions)	8.6	(0.3)	2.2
Uncollectible accounts written off	(11.2)	(11.9)	(7.1)
Accounts Receivable, Allowance for Credit Loss, Recovery	0.2
Foreign currency translation adjustment	1.0	(0.2)	(1.8)
Balance at end of period	$ 98.3	$ 40.2	$ 42.5
New Accounting Pronouncement or Change in Accounting Principle, Description	9.0

Supplementary Data Property and Equipment (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Oct. 01, 2018
Property and Equipment [Abstract]
Depreciation	$ 204.7	$ 192.5	$ 165.3
Property, Plant and Equipment [Line Items]
Furniture and equipment	654.6	694.3
Leasehold improvements	554.6	634.9
Internal-use computer software	470.1	422.0
Land and buildings	144.9	143.3
Total property and equipment, gross	1,824.2	1,894.5
Less: accumulated depreciation and amortization	(1,133.9)	(1,116.4)
Total property and equipment, net	$ 690.3	$ 778.1		$ 159.7

Accrued Liabilities (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Accrued Liabilities [Abstract]
Salaries, benefits and related expenses	$ 504.6	$ 494.1
Restructuring Reserve, Current	69.5	1.6
Office and related expenses	25.5	26.9
Acquisition obligations	47.9	45.7
Interest	43.6	38.8
Accrued Income Taxes	50.6	43.2
Other	90.7	92.5
Total accrued liabilities	$ 832.4	$ 742.8

Other Expense, Net (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
Other Expense, Net (Details) - USD ($) $ in Millions	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Other Nonoperating Income (Expense) [Abstract]
Net losses on sales of businesses	$ 15.2	$ 8.6	$ 19.9	$ 23.3	$ 23.9	$ 7.7	$ 3.2	$ 8.6	$ (67.0)	$ (43.4)	$ (61.9)
Other									2.6	0.5	(7.7)
Total other expense, net	$ (9.8)	$ (11.3)	$ (21.5)	$ (21.8)	$ (24.8)	$ (7.4)	$ (3.8)	$ (6.9)	(64.4)	(42.9)	(69.6)
Proceeds from Divestiture of Businesses, Net of Cash Divested									$ 62.9	$ 6.7	$ 30.8

Share Repurchase Program (Details) - USD ($) $ in Millions	12 Months Ended
Share Repurchase Program (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2020
Aggregate cost, including fees	$ 117.1
2017 Share Repurchase Program
Stock repurchase program, remaining authorized repurchase amount		$ 338.4

Goodwill (Details) - USD ($) $ in Millions	12 Months Ended
Goodwill (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Oct. 01, 2018
Goodwill
Goodwill	$ 4,945.5	$ 4,894.4	$ 4,875.9	$ 1,110.8
Current year acquisitions	24.0	2.8
Foreign currency and other	27.1	15.7
IAN
Goodwill
Goodwill	4,264.5	4,218.1	4,201.5
Current year acquisitions	23.5	2.1
Foreign currency and other	22.9	14.5
DXTRA
Goodwill
Goodwill	681.0	676.3	$ 674.4
Current year acquisitions	0.5	0.7
Foreign currency and other	$ 4.2	$ 1.2

Other Intangible Assets (Details) - USD ($) $ in Millions	12 Months Ended
Other Intangible Assets (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Oct. 01, 2018
Goodwill and Intangible Assets Disclosure [Abstract]
Future amortization expense 2018	$ 88.3
Future amortization expense 2019	83.8
Future amortization expense 2020	79.0
Future amortization expense 2021	77.3
Future amortization expense 2022	74.5
Finite-Lived Intangible Assets [Line Items]
Amortization of Intangible Assets	85.9	$ 86.0	$ 37.6
Acquired finite-lived intangible assets related to acquisitions	4.0	5.0
Gross Amount	1,333.9	1,336.9
Accumulated Amortization	(400.3)	(322.6)
Net Amount	933.6	$ 1,014.3
Customer lists
Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Asset, Useful Life		15 years
Gross Amount	859.5	$ 861.4		$ 600.0
Accumulated Amortization	(293.3)	(244.6)
Net Amount	566.2	$ 616.8
know-how technology
Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Asset, Useful Life		9 years
Gross Amount	224.4	$ 226.2		235.0
Accumulated Amortization	(44.1)	(41.3)
Net Amount	176.5	202.1
Trade names
Finite-Lived Intangible Assets [Line Items]
Gross Amount	235.4	235.0		$ 995.0
Accumulated Amortization	(58.9)	(32.9)
Net Amount	180.3	184.9
Other intangible assets
Finite-Lived Intangible Assets [Line Items]
Gross Amount	14.6	14.3
Accumulated Amortization	(4.0)	(3.8)
Net Amount	$ 10.6	$ 10.5
Minimum
Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Asset, Useful Life	7 years
Maximum
Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Asset, Useful Life	15 years

Components of Income Before Income Taxes (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Income before income taxes, Domestic	$ 279.9	$ 557.4	$ 474.0
Income before income taxes, Foreign	81.4	320.9	364.0
Income before income taxes	$ 361.3	$ 878.3	$ 838.0

Provision for Income Taxes (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
U.S. federal income taxes (including foreign withholding taxes):
Current federal income taxes									$ (52.6)	$ 92.2	$ 38.1
Deferred federal income taxes									(12.0)	9.5	29.9
Total federal income taxes									(64.6)	101.7	68.0
State and local income taxes:
Current state and local income taxes									(3.7)	10.7	25.1
Deferred state and local income taxes									0.5	8.7	3.4
Total state and local income taxes									(3.2)	19.4	28.5
Foreign income taxes:
Current foreign income taxes									110.7	92.2	121.9
Deferred foreign income taxes									(34.9)	(8.5)	(19.2)
Total foreign income taxes									75.8	83.7	102.7
Provision for income taxes	$ 58.1	$ (86.3)	$ 19.0	$ 17.2	$ 86.1	$ 64.6	$ 43.6	$ 10.5	$ 8.0	$ 204.8	$ 199.2

Reconciliation of Effective Income Tax Rate (Details) - USD ($)
$ in Millions

3 Months Ended

12 Months Ended

Dec. 31, 2020

Sep. 30, 2020

Jun. 30, 2020

Mar. 31, 2020

Dec. 31, 2019

Sep. 30, 2019

Jun. 30, 2019

Mar. 31, 2019

Dec. 31, 2020

Dec. 31, 2019

Dec. 31, 2018

Effective Income Tax Rate Reconciliation, Percent [Abstract]

U.S. federal statutory income tax rate

21.00%

Income tax provision at U.S. federal statutory rate

$ 75.9

$ 184.5

$ 176.0

State and local income taxes, net of federal income tax benefit

9.4

14.0

23.8

Impact of foreign operations, including withholding taxes

49.9

34.2

50.7

U.S. tax incentives

(23.6)

(21.4)

(17.5)

Change in net valuation allowance

^[1]

(1.3)

(26.3)

(16.9)

Divestitures

8.6

9.6

11.7

U.S. federal tax credits

(1.7)

0.4

(48.1)

Change in unrecognized tax benefits

30.8

14.1

8.4

Net impact of the Tax Act

0.0

13.4

Other

(3.8)

(4.3)

(2.3)

Provision for income taxes

$ 58.1

$ (86.3)

$ 19.0

$ 17.2

$ 86.1

$ 64.6

$ 43.6

$ 10.5

$ 8.0

$ 204.8

$ 199.2

Effective income tax rate on operations

2.20%

23.30%

23.80%

Tax Adjustments, Settlements, and Unusual Provisions

$ 136.2

$ 13.9

$ (136.2)

$ 0.0

[1]	Reflects changes in valuation allowances that impacted the effective income tax rate for each year presented.

Income Taxes Primary Impact on Provision for Income Taxes (Details) - USD ($) $ in Millions	3 Months Ended			12 Months Ended
	Sep. 30, 2020	Dec. 31, 2019	Jun. 30, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Effective Income Tax Rate Reconciliation, Percent				2.20%	23.30%	23.80%
Previously unrecognized tax benefits	$ 136.2		$ 13.9	$ (136.2)	$ 0.0	$ 0.0
Reversal of valuation allowance		$ 25.3

Components of Deferred Tax Assets (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Deferred Tax Assets, Net [Abstract]
Postretirement/post-employment benefits	$ 16.6	$ 16.7
Deferred compensation	106.5	99.5
Pension costs	27.9	23.7
Basis differences in fixed assets	(86.3)	(75.3)
Interest	42.9	45.5
Accruals and reserves	23.9	19.4
Allowance for doubtful accounts	19.7	6.5
Basis differences in intangible assets	(340.0)	(321.0)
Deferred Tax Liabilities, ROU	(285.8)	(335.2)
Deferred Tax Liabilities, Leasing Arrangements	350.4	361.4
Tax loss/tax credit carry forwards	343.0	297.1
Prepaid expenses	(7.3)	(6.7)
Deferred revenue	(11.6)	(21.7)
Unremitted foreign earnings	(9.3)	(1.3)
Deferred Tax and Other Liabilities, Noncurrent	(740.3)	(761.2)
Other	83.6	44.8
Net deferred tax assets	1,014.5	914.6
Valuation allowance	(197.1)	(164.2)	$ (211.0)	$ (243.0)
Deferred Tax Assets, Net	77.1	(10.8)
Total deferred tax assets, net	817.4	750.4
Foreign Income Tax Expense (Benefit), Continuing Operations	75.8	83.7	$ 102.7
Deferred Tax Assets	302.0	252.1
Deferred income taxes	302.0	252.1
Deferred Tax Liabilities	$ 224.9	$ 262.8

Income Taxes Change in Valuation Allowances (Details) - USD ($)
$ in Millions

12 Months Ended

Dec. 31, 2020

Dec. 31, 2019

Dec. 31, 2018

Oct. 01, 2018

Summary of Valuation Allowances

Net impact of the Tax Act

$ 0.0

$ 13.4

Beginning balance

164.2

211.0

243.0

Charged (reversed ) to costs and expenses

17.3

(24.9)

(28.0)

Charged (reversed) to gross tax assets and other accounts 1

^[1]

9.9

(19.8)

5.1

Foreign currency translation

5.7

(2.1)

(9.1)

Ending balance

197.1

164.2

211.0

Foreign Income Tax Expense (Benefit), Continuing Operations

75.8

83.7

$ 102.7

Deferred Tax Assets, Operating Loss Carryforwards, Components [Abstract]

Operating Loss Carryforwards

1,188.8

Undistributed Earnings of Foreign Subsidiaries

1,080.2

1,199.7

$ 435.0

Other Tax Expense (Benefit)

10.8

Changes in non-US tax law [Member]

Summary of Valuation Allowances

Foreign Income Tax Expense (Benefit), Continuing Operations

10.4

Deferred Tax Assets, Operating Loss Carryforwards, Components [Abstract]

Undistributed Earnings of Foreign Subsidiaries

120.0

Restructuring actions taken within foreign subsidiaries [Member]

Summary of Valuation Allowances

Foreign Income Tax Expense (Benefit), Continuing Operations

3.2

Deferred Tax Assets, Operating Loss Carryforwards, Components [Abstract]

Undistributed Earnings of Foreign Subsidiaries

$ 46.0

Foreign Tax Authority

Deferred Tax Assets, Operating Loss Carryforwards, Components [Abstract]

Deferred Tax Assets, Operating Loss Carryforwards, Not Subject to Expiration

1,035.3

Deferred Tax Assets, Operating Loss Carryforwards, Subject to Expiration

153.5

State and Local Jurisdiction

Deferred Tax Assets, Operating Loss Carryforwards, Components [Abstract]

Deferred Tax Assets, Operating Loss Carryforwards, Subject to Expiration

$ 31.4

[1]	Primarily represents changes to the valuation allowance related to the change of a corresponding deferred tax asset.

Unrecognized Tax Benefits (Details) - USD ($) $ in Millions	12 Months Ended
Unrecognized Tax Benefits (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Unrecognized Tax Benefits, Income Tax Penalties and Interest Accrued [Abstract]
Balance at beginning of period	$ 345.3	$ 335.4	$ 271.9
Increases as a result of tax positions taken during a prior year	18.1	22.7	65.9
Decreases as a result of tax positions taken during a prior year	(165.7)	(25.8)	(10.8)
Settlements with taxing authorities	(6.2)	(8.1)	(6.5)
Lapse of statutes of limitation	(0.7)	(0.6)	(1.7)
Increases as a result of tax positions taken during the current year	26.8	21.7	16.6
Balance at end of period	217.6	345.3	$ 335.4
Income Tax Contingency [Line Items]
Unrecognized tax benefits that would impact effective tax rate	188.9
Income tax penalties and interest accrued	33.4	39.6
Income tax penalties and interest expense	6.2	(2.8)
Deferred Tax and Other Liabilities, Noncurrent	740.3	$ 761.2
Minimum [Member]
Income Tax Contingency [Line Items]
Anticipated decrease in unrecognized tax benefits	20.0
Maximum [Member]
Income Tax Contingency [Line Items]
Anticipated decrease in unrecognized tax benefits	$ 30.0

Accumulated Other Comprehensive Loss, Net of Tax Changes in AOCI (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Accumulated Other Comprehensive Income (Loss) [Line Items]
Derivative instruments, before reclassifications	$ 11.3	$ 0.0	$ 0.0
Total other comprehensive income, before reclassifications	22.3	(2.7)
Total reclassification from AOCI	27.5	13.8	22.1
Accumulated other comprehensive loss, net of tax	(880.2)	(930.0)	(941.1)
Foreign Currency Translation Adjustment
Accumulated Other Comprehensive Income (Loss) [Line Items]
Foreign currency translation adjustment, before reclassifications	40.1	12.0
Foreign currency translation adjustment, amount reclassified from AOCI, net of tax	20.0	6.7
Foreign currency translation adjustment, net of tax	(637.6)	(697.7)	(716.4)
Derivative Instruments
Accumulated Other Comprehensive Income (Loss) [Line Items]
Derivative instruments, before reclassifications	8.5	0.0
Derivative instruments, amount reclassified from AOCI, net of tax	1.8	1.8
Derivative Instruments, net of tax	6.8	(3.5)	(5.3)
Defined Benefit and Postretirement Plans
Accumulated Other Comprehensive Income (Loss) [Line Items]
Defined Benefit and Postretirement Plans, before reclassifications	(26.3)	(14.7)
Defined benefit and Postretirement Plans, amount reclassified from AOCI, net of tax	5.7	5.3
Pension and Other Postretirement Benefit Plans, net of tax	$ (249.4)	$ (228.8)	$ (219.4)

Accumulated Other Comprehensive Loss, Net of Tax Reclassifications from AOCI, net of tax (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Total income tax effect	$ (2.2)	$ (1.9)	$ (2.3)
Total reclassified from AOCI, net of tax	27.5	13.8	22.1
Foreign Currency Translation Adjustment
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Reclassification from AOCI, before tax	20.0	6.7	15.7
Derivative Instruments
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Reclassification from AOCI, before tax	2.4	2.3	2.2
Defined Benefit and Postretirement Plans
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Reclassification from AOCI, before tax	$ 7.3	$ 6.7	$ 6.5

- Definition

Amount of tax expense (benefit) allocated to other comprehensive income (loss).

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 20
-Section 45
-Paragraph 11
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=120385591&loc=d3e39076-109324

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 830
-SubTopic 30
-Section 45
-Paragraph 17
-URI http://asc.fasb.org/extlink&oid=118261656&loc=d3e32136-110900

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 830
-SubTopic 30
-Section 45
-Paragraph 20
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=118261656&loc=d3e32211-110900

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 20
-Section 45
-Paragraph 2
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=120385591&loc=d3e38679-109324

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 220
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-04(23))
-URI http://asc.fasb.org/extlink&oid=120399700&loc=SL114874048-224260

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
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-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
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-Paragraph 2
-Subparagraph (SX 210.5-03(21))
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Reference 7: http://www.xbrl.org/2003/role/disclosureRef
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-Name Accounting Standards Codification
-Topic 740
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Reference 8: http://www.xbrl.org/2003/role/disclosureRef
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-Name Accounting Standards Codification
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-Section 50
-Paragraph 1
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Reference 9: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section 45
-Paragraph 12
-URI http://asc.fasb.org/extlink&oid=121641772&loc=d3e640-108580

Reference 10: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 220
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-04(19))
-URI http://asc.fasb.org/extlink&oid=120400993&loc=SL114874131-224263

+ Details

Restructuring Charges (Details) - USD ($)	3 Months Ended								12 Months Ended
Restructuring Charges (Details) - USD ($)	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Restructuring Cost and Reserve [Line Items]
Severance and termination costs									$ 140,400,000	$ 22,000,000.0	$ 0.0
Lease Restructuring Cost									256,000,000.0	11,900,000	0.0
Other Restructuring Costs									17,400,000	0.0	0.0
Restructuring Charges	$ 253,900,000	$ 47,300,000	$ 112,600,000	$ 0.0	$ 0.0	$ 0.0	$ 2,100,000	$ 31,800,000	413,800,000	$ 33,900,000	$ 0.0
Non-cash Items [Member]
Restructuring Cost and Reserve [Line Items]
Severance and termination costs									4,500,000
Lease Restructuring Cost									256,000,000.0
Other Restructuring Costs									5,100,000
Restructuring Charges									265,600,000
Cash Payments [Member]
Restructuring Cost and Reserve [Line Items]
Severance and termination costs									61,300,000
Lease Restructuring Cost									0.0
Other Restructuring Costs									12,300,000
Restructuring Charges									$ 73,600,000

Restructuring and Related Activities (Details)	3 Months Ended								12 Months Ended
Restructuring and Related Activities (Details)	Dec. 31, 2020 USD ($) ft²	Sep. 30, 2020 USD ($)	Jun. 30, 2020 USD ($)	Mar. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)	Sep. 30, 2019 USD ($)	Jun. 30, 2019 USD ($)	Mar. 31, 2019 USD ($)	Dec. 31, 2020 USD ($) ft² numberOfPeople	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)
Restructuring Cost and Reserve [Line Items]
Severance and termination costs									$ 140,400,000	$ 22,000,000.0	$ 0.0
Lease Restructuring Cost									256,000,000.0	11,900,000	0.0
Other Restructuring Costs									17,400,000	0.0	0.0
Restructuring Charges	$ 253,900,000	$ 47,300,000	$ 112,600,000	$ 0.0	$ 0.0	$ 0.0	$ 2,100,000	$ 31,800,000	413,800,000	$ 33,900,000	$ 0.0
Restructuring Reserve	$ 74,600,000								$ 74,600,000
Restructuring and Related Cost, Number of Positions Eliminated \| numberOfPeople									1,520
Restructuring and Related Cost, Number of Positions Eliminated, Inception to Date Percent	3.00%								3.00%
Area of Real Estate Property \| ft²	1,700,000								1,700,000
IAN
Restructuring Cost and Reserve [Line Items]
Lease Restructuring Cost									$ 190,400,000
Restructuring Charges									317,900,000
DXTRA
Restructuring Cost and Reserve [Line Items]
Lease Restructuring Cost									59,800,000
Restructuring Charges									78,800,000
Non-cash Items [Member]
Restructuring Cost and Reserve [Line Items]
Severance and termination costs									4,500,000
Lease Restructuring Cost									256,000,000.0
Other Restructuring Costs									5,100,000
Restructuring Charges									265,600,000
Cash Payments [Member]
Restructuring Cost and Reserve [Line Items]
Severance and termination costs									61,300,000
Lease Restructuring Cost									0.0
Other Restructuring Costs									12,300,000
Restructuring Charges									73,600,000
Employee Severance [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Reserve	$ 74,600,000								74,600,000
Lease impairment costs [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Reserve	0.0								0.0
Other Restructuring [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Reserve	$ 0.0								$ 0.0

Plan Information (Details) - USD ($) shares in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Deferred Compensation Liability, Current and Noncurrent	$ 188.5	$ 197.5
Incentive compensation plan initiation year	2019
2019 PIP target performance cash award percentage range	range from 0% to 300% of the target amount
2019 PIP target award percentage range - Executives	0% to 200%
Number of shares initially available for grant	27.0
Maximum shares participants are eligible to receive	2.0
Maximum cash award per employee	$ 10.0
Vesting period in which the fair value of shares on grant date is amortized over, years	two years

Stock Based Compensation Expense (Details) - USD ($)
$ in Millions

12 Months Ended

Dec. 31, 2020

Dec. 31, 2019

Dec. 31, 2018

Stock-based Payment Award

Stock-based compensation expense

$ 71.1

$ 82.7

$ 84.6

Tax benefit

17.3

20.0

20.4

Stock-settled awards

Stock-based Payment Award

Stock-based compensation expense

38.4

33.5

24.7

Cash-settled awards

Stock-based Payment Award

Stock-based compensation expense

1.0

0.8

0.6

Performance-based awards

Stock-based Payment Award

Stock-based compensation expense

28.6

46.7

57.5

Employee stock purchase plan

Stock-based Payment Award

Stock-based compensation expense

1.4

1.1

0.9

Other

Stock-based Payment Award

Stock-based compensation expense

^[1]

$ 1.7

$ 0.6

$ 0.9

[1]	Represents charges recorded for severance expense related to stock-based compensation awards.

Incentive Compensation Plans Stock Option Activity (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Stock-based Payment Award
Intrinsic value of stock options exercised	$ 5.3	$ 9.1	$ 27.9
Proceeds from stock options exercised including taxes withheld	9.1	8.3	29.0
Tax withheld on stock options received	$ 2.6	$ 4.0	$ 13.3
Employee Stock Option
Stock-based Payment Award
Stock options outstanding as of January 1, 2018	1.2
Stock options outstanding as of Jan 1, 2018, Weighted-average exercise price	$ 12.26
Exercised	(0.6)	(0.6)	(1.9)
Exercised, weighted-average exercise price	$ 11.70
Stock options outstanding as of December 31, 2018	0.6	1.2
Stock options outstanding as of Dec 31, 2018, Weighted-average exercise price	$ 12.75	$ 12.26
Options outstanding, weighted average remaining contractual term	2 years 2 months 12 days
Stock options outstanding, aggregate intrinsic value	$ 6.8

Share-based Compensation Awards (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Stock-based Payment Award
Vesting period in which the fair value of shares on grant date is amortized over, years	two years
Stock-settled awards
Stock-based Payment Award
Awards granted	2.3	2.5	2.1
Weighted-average grant-date fair value (per award)	$ 20.70	$ 22.78	$ 23.60
Total fair value of vested awards distributed	$ 17.3	$ 15.2	$ 24.2
Accrued dividends on non-vested stock-settled awards	5.6	4.2
Dividends paid for stock-settled awards	$ 1.5	$ 1.2
Cash-settled awards
Stock-based Payment Award
Awards granted	0.0	0.0	0.1
Weighted-average grant-date fair value (per award)	$ 21.02	$ 22.83	$ 23.62
Total fair value of vested awards distributed	$ 0.3	$ 0.9	$ 0.8
Performance-based awards
Stock-based Payment Award
Awards granted	2.4	2.1	2.9
Weighted-average grant-date fair value (per award)	$ 18.67	$ 20.16	$ 21.13
Total fair value of vested awards distributed	$ 53.3	$ 64.9	$ 87.2

Non-vested Award Activity (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Stock-settled awards
Stock-based Payment Award
Non-vested as of January 1, 2018	4.7
Nonvested as of January 1, 2018, weighted-average grant date fair value	$ 23.21
Granted	2.3
Granted, Weighted-average grant-date fair value	$ 20.70	$ 22.78	$ 23.60
Vested	(0.9)
Vested, Weighted-average grant date fair value	$ 23.71
Forfeited	(0.4)
Forfeited, Weighted-average grant date fair value	$ 22.55
Non-vested as of December 31, 2018	5.7	4.7
Nonvested as of December 31, 2018, weighted-average grant date fair value	$ 22.18	$ 23.21
Total unrecognized compensation expense remaining	$ 48.5
Weighted-average years expected to be recognized over	1 year 2 months 12 days
Cash-settled awards
Stock-based Payment Award
Non-vested as of January 1, 2018	0.1
Nonvested as of January 1, 2018, weighted-average grant date fair value	$ 23.20
Granted	0.0
Granted, Weighted-average grant-date fair value	$ 21.02	$ 22.83	$ 23.62
Vested	0.0
Vested, Weighted-average grant date fair value	$ 22.12
Forfeited	0.0
Forfeited, Weighted-average grant date fair value	$ 23.14
Non-vested as of December 31, 2018	0.1	0.1
Nonvested as of December 31, 2018, weighted-average grant date fair value	$ 22.40	$ 23.20
Total unrecognized compensation expense remaining	$ 1.1
Weighted-average years expected to be recognized over	1 year 1 month 6 days
Cash awards granted during the period target value	$ 54.5	$ 22.3	$ 20.9
Incentive compensation expense, non share-based	$ 25.5	$ 15.6	$ 7.0
Performance-based awards
Stock-based Payment Award
Non-vested as of January 1, 2018	5.6
Nonvested as of January 1, 2018, weighted-average grant date fair value	$ 21.36
Granted	2.4
Granted, Weighted-average grant-date fair value	$ 18.67	$ 20.16	$ 21.13
Vested	(2.6)
Vested, Weighted-average grant date fair value	$ 22.18
Forfeited	(0.6)
Forfeited, Weighted-average grant date fair value	$ 21.12
Non-vested as of December 31, 2018	4.8	5.6
Nonvested as of December 31, 2018, weighted-average grant date fair value	$ 19.61	$ 21.36
Total unrecognized compensation expense remaining	$ 33.9
Weighted-average years expected to be recognized over	1 year 9 months 18 days
Cash awards granted during the period target value	$ 43.5	$ 40.7	$ 39.9
Incentive compensation expense, non share-based	$ 29.2	$ 39.9	$ 37.6

Incentive Compensation Plans Employee Stock Purchase Plans (Details) - shares	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2017
Employee Stock Ownership Plan (ESOP), Shares in ESOP [Abstract]
Maximum employee subscription rate	10.00%
Maximum number of shares per employee	900
Employee stock purchase plan description	90% of the lesser of the average market price of a share on the first business day of the offering period or the average market price of a share on the last business day of the offering period of three months
Employee Stock Purchase Plan, stock issued, shares	1,600,000	3,000,000.0
Employee Stock Purchase Plan, stock reserved for issuance, shares	10,000,000.0

Fair Value on a Recurring Basis (Details) - USD ($)
$ in Millions

12 Months Ended

Dec. 31, 2020

Dec. 31, 2019

Fair value assets and liabilities measured on recurring basis

Cash equivalents

$ 1,507.4

$ 786.0

Contingent acquisition obligations

^[1]

95.5

114.1

Contingent acquisition obligation, total change

$ (18.6)

Discount rate floor contingent acquisition obligations

1.00%

Discount rate floor long-term debt

0.40%

Discount rate ceiling long-term debt

3.40%

Level 1

Fair value assets and liabilities measured on recurring basis

Cash equivalents

$ 1,507.4

786.0

Contingent acquisition obligations

^[1]

0.0

Level 2

Fair value assets and liabilities measured on recurring basis

Cash equivalents

0.0

Contingent acquisition obligations

^[1]

0.0

Level 3

Fair value assets and liabilities measured on recurring basis

Cash equivalents

0.0

Contingent acquisition obligations

^[1]

$ 95.5

$ 114.1

[1]

Contingent acquisition obligations includes deferred acquisition payments and unconditional obligations to purchase additional noncontrolling equity shares of consolidated subsidiaries. Fair value measurement of the obligations is based upon actual and projected operating performance targets as specified in the related agreements. The decrease in this balance of $18.6 from December 31, 2019 to December 31, 2020 is primarily due to payments. The amounts payable within the next twelve months are classified in accrued liabilities; any amounts payable thereafter are classified in other non-current liabilities.

Fair Value on a Nonrecurring Basis (Details) - USD ($)	12 Months Ended
Fair Value on a Nonrecurring Basis (Details) - USD ($)	Dec. 31, 2020	Dec. 31, 2019
Fair value assets and liabilities measured on nonrecurring basis
Long-term debt, fair value	$ 3,995,000,000.0	$ 3,565,500,000
Discount rate ceiling contingent acquisition obligations	4.00%
Level 1
Fair value assets and liabilities measured on nonrecurring basis
Long-term debt, fair value	$ 0.0
Level 2
Fair value assets and liabilities measured on nonrecurring basis
Long-term debt, fair value	3,951,100,000
Level 3
Fair value assets and liabilities measured on nonrecurring basis
Long-term debt, fair value	$ 43,900,000

Employee Benefits (Details) $ in Millions	12 Months Ended
Employee Benefits (Details) $ in Millions	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)
Retirement Benefits, Description [Abstract]
Number of participants domestic pension plan	3,100
Number of participants postretirement benefit plan	1,400
Deferred Compensation Arrangements [Abstract]
Deferred compensation and benefit liability balance	$ 188.5	$ 197.5
Deferred compensation and benefit arrangement expense	11.0	19.4	$ 10.0
Cash Surrender Value of Life Insurance	180.8	178.2
Long-Term Disability Plan [Abstract]
Long-term disability plan obligation	8.7	$ 5.5
Long term disability plan, income replacement benefit obligation	$ 0.0

Pension and Postretirement Benefit Obligation (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Benefit Obligation [Roll Forward]
Domestic Pension Plan Discount Rate	2.60%	3.35%
Fair Value of Plan Assets [Roll Forward]
Fair Value of Plan Assets (Period Start)	$ 508.6
Fair Value of Plan Assets (Period End)	$ 562.5	$ 508.6
Pension plans with underfunded or unfunded accumulated benefit obligation
Foreign Pension Plan Discount Rate	1.35%	1.84%
Domestic Plan [Member]
Benefit Obligation [Roll Forward]
Benefit obligation (period start)	$ 116.9	$ 115.4
Service cost	0.0	0.0	$ 0.0
Interest cost	3.7	4.8	4.5
Benefits Paid	(10.1)	(9.2)
Plan participant contributions	0.0	0.0
Actuarial losses (gains)	6.3	5.9
Settlements and curtailments	0.0	0.0
Foreign currency effect	0.0	0.0
Other	0.0	0.0
Benefit Obligation (Period End)	116.8	116.9	115.4
Fair Value of Plan Assets [Roll Forward]
Fair Value of Plan Assets (Period Start)	99.1	89.8
Actual return on plan assets	10.6	16.1
Plan participant contributions	0.0	0.0
Employer contributions	1.3	2.4
Benefits paid	(10.1)	(9.2)
Settlements	0.0	0.0
Foreign currency effect	0.0	0.0
Fair Value of Plan Assets (Period End)	100.9	99.1	$ 89.8
Defined Benefit Plan, Funded (Unfunded) Status of Plan	(15.9)	(17.8)
Amounts Recognized in Consolidated Balance Sheets
Non-current asset	0.0	0.0
Current liability	0.0	0.0
Non-current liability	(15.9)	(17.8)
Net liability recognized	(15.9)	(17.8)
Accumulated benefit obligation	116.8	116.9
Amounts recognized in Accumulated Other Comprehensive Loss, net
Net actuarial loss	53.9	54.2
Prior service cost (credit)	0.0	0.0
Total amount recognized	53.9	54.2
Pension plans with underfunded or unfunded accumulated benefit obligation
Aggregate projected benefit obligation	116.8	116.9
Aggregate accumulated benefit obligation	116.8	116.9
Aggregate fair value of plan assets	$ 100.9	$ 99.1
Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Discount Rate	2.60%	3.35%	4.35%
Foreign Plan [Member]
Benefit Obligation [Roll Forward]
Benefit obligation (period start)	$ 541.2	$ 496.0
Service cost	4.9	4.8	$ 5.4
Interest cost	9.4	12.4	13.1
Benefits Paid	(22.9)	(27.8)
Plan participant contributions	0.0	0.0
Actuarial losses (gains)	54.3	42.7
Defined Benefit Plan, Benefit Obligation, Increase (Decrease) for Plan Amendment	(4.9)	(0.7)
Foreign currency effect	23.3	13.8
Other	0.6	0.0
Benefit Obligation (Period End)	605.9	541.2	496.0
Fair Value of Plan Assets [Roll Forward]
Fair Value of Plan Assets (Period Start)	409.5	363.9
Actual return on plan assets	45.7	42.0
Plan participant contributions	0.0	0.0
Employer contributions	18.4	18.0
Benefits paid	(22.9)	(27.8)
Settlements	(4.9)	0.0
Foreign currency effect	15.8	13.4
Fair Value of Plan Assets (Period End)	461.6	409.5	$ 363.9
Defined Benefit Plan, Funded (Unfunded) Status of Plan	(144.3)	(131.7)
Amounts Recognized in Consolidated Balance Sheets
Non-current asset	10.9	10.1
Current liability	(7.4)	(5.8)
Non-current liability	(147.8)	(136.0)
Net liability recognized	(144.3)	(131.7)
Accumulated benefit obligation	603.3	538.6
Amounts recognized in Accumulated Other Comprehensive Loss, net
Net actuarial loss	213.3	183.2
Prior service cost (credit)	1.1	1.1
Total amount recognized	214.4	184.3
Pension plans with underfunded or unfunded accumulated benefit obligation
Aggregate projected benefit obligation	600.8	534.6
Aggregate accumulated benefit obligation	600.1	533.5
Aggregate fair value of plan assets	$ 445.6	$ 392.7
Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Discount Rate	1.35%	1.84%	2.61%
Other Postretirement Benefits Plan [Member]
Benefit Obligation [Roll Forward]
Benefit obligation (period start)	$ 27.2	$ 27.7
Service cost	0.0	0.0	$ 0.0
Interest cost	0.8	1.2	1.1
Benefits Paid	(5.2)	(5.4)
Plan participant contributions	2.1	2.0
Actuarial losses (gains)	0.9	1.7
Settlements and curtailments	0.0	0.0
Foreign currency effect	0.0	0.0
Other	0.0	0.0
Benefit Obligation (Period End)	25.8	27.2	27.7
Fair Value of Plan Assets [Roll Forward]
Fair Value of Plan Assets (Period Start)	0.0	0.0
Actual return on plan assets	0.0	0.0
Plan participant contributions	2.1	2.0
Employer contributions	3.1	3.4
Benefits paid	(5.2)	(5.4)
Settlements	0.0	0.0
Foreign currency effect	0.0	0.0
Fair Value of Plan Assets (Period End)	0.0	0.0	$ 0.0
Defined Benefit Plan, Funded (Unfunded) Status of Plan	(25.8)	(27.2)
Amounts Recognized in Consolidated Balance Sheets
Non-current asset	0.0	0.0
Current liability	(2.5)	(2.7)
Non-current liability	(23.3)	(24.5)
Net liability recognized	(25.8)	(27.2)
Amounts recognized in Accumulated Other Comprehensive Loss, net
Net actuarial loss	5.4	4.7
Prior service cost (credit)	0.0	(0.1)
Total amount recognized	$ 5.4	$ 4.6
Pension plans with underfunded or unfunded accumulated benefit obligation
Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Discount Rate	2.50%	3.25%	4.30%

Net Periodic Cost (Details) - USD ($) $ in Millions	12 Months Ended
Net Periodic Cost (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Defined Benefit Plan, Net Periodic Benefit Cost
Settlement and curtailment	$ 0.1	$ (0.0)	$ 1.0
Domestic Plan [Member]
Defined Benefit Plan, Net Periodic Benefit Cost
Service cost	0.0	0.0	0.0
Interest cost	3.7	4.8	4.5
Expected return on plan assets	(5.7)	(5.9)	(6.6)
Settlement and curtailment	0.0	0.0	0.0
Amortization of:
Prior service cost (credit)	0.0	0.0	0.0
Net actuarial losses	1.7	1.9	1.6
Defined Benefit Plan, Net Periodic Benefit Cost (Credit)	$ (0.3)	$ 0.8	$ (0.5)
Discount rate	3.35%	4.35%	3.70%
Expected return on plan assets	6.00%	7.00%	7.00%
Interest crediting rate	5.10%	5.10%	5.10%
Discount rate	2.60%	3.35%	4.35%
Interest crediting rate	5.10%	5.10%	5.10%
Foreign Plan [Member]
Defined Benefit Plan, Net Periodic Benefit Cost
Service cost	$ 4.9	$ 4.8	$ 5.4
Interest cost	9.4	12.4	13.1
Expected return on plan assets	(18.8)	(17.4)	(18.8)
Settlement and curtailment	(0.1)	0.0	(1.0)
Amortization of:
Prior service cost (credit)	0.1	0.1	0.1
Net actuarial losses	5.4	4.8	5.9
Defined Benefit Plan, Net Periodic Benefit Cost (Credit)	$ 0.9	$ 4.7	$ 4.7
Discount rate	1.84%	2.61%	2.36%
Rate of compensation increase	2.51%	2.58%	2.37%
Expected return on plan assets	4.70%	4.76%	4.70%
Interest crediting rate	1.37%	1.44%	1.31%
Discount rate	1.35%	1.84%	2.61%
Rate of compensation increase	2.47%	2.51%	2.58%
Interest crediting rate	1.50%	1.37%	1.44%
Other Postretirement Benefits Plan [Member]
Defined Benefit Plan, Net Periodic Benefit Cost
Service cost	$ 0.0	$ 0.0	$ 0.0
Interest cost	0.8	1.2	1.1
Expected return on plan assets	0.0	0.0	0.0
Settlement and curtailment	0.0	0.0	0.0
Amortization of:
Prior service cost (credit)	0.0	(0.2)	(0.2)
Net actuarial losses	0.2	0.1	0.1
Defined Benefit Plan, Net Periodic Benefit Cost (Credit)	$ 1.0	$ 1.1	$ 1.0
Discount rate	3.25%	4.30%	3.65%
Discount rate	2.50%	3.25%	4.30%
Health care cost trend rate assumed for next year	6.75%	7.00%	6.25%
Year ultimate rate is reached	2028	2028	2024
Ultimate rate	5.00%	5.00%	5.00%

Fair Value of Pension Plan Assets (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Fair value assets and liabilities measured on recurring basis
Fair Value of Plan Assets (Period Start)	$ 508.6
Fair Value of Plan Assets (Period End)	562.5	$ 508.6
Investment funds
Fair value assets and liabilities measured on recurring basis
Fair Value of Plan Assets (Period Start)	18.0
Fair Value of Plan Assets (Period End)	19.3	18.0
Limited partnerships
Fair value assets and liabilities measured on recurring basis
Fair Value of Plan Assets (Period Start)	25.6
Fair Value of Plan Assets (Period End)	25.9	25.6
Fixed income securities
Fair value assets and liabilities measured on recurring basis
Fair Value of Plan Assets (Period Start)	19.6
Fair Value of Plan Assets (Period End)	22.7	19.6
Insurance contracts
Fair value assets and liabilities measured on recurring basis
Fair Value of Plan Assets (Period Start)	5.5
Fair Value of Plan Assets (Period End)	3.6	5.5
Other plan assets
Fair value assets and liabilities measured on recurring basis
Fair Value of Plan Assets (Period Start)	27.8
Fair Value of Plan Assets (Period End)	28.9	27.8
Total plan assets subject to leveling
Fair value assets and liabilities measured on recurring basis
Fair Value of Plan Assets (Period Start)	96.5
Fair Value of Plan Assets (Period End)	100.4	96.5
Investments measured at net asset value
Fair value assets and liabilities measured on recurring basis
Fair Value of Plan Assets (Period Start)	412.1
Fair Value of Plan Assets (Period End)	462.1	412.1
Level 1 \| Investment funds
Fair value assets and liabilities measured on recurring basis
Fair Value of Plan Assets (Period Start)	18.0
Fair Value of Plan Assets (Period End)	19.3	18.0
Level 1 \| Limited partnerships
Fair value assets and liabilities measured on recurring basis
Fair Value of Plan Assets (Period Start)	0.0
Fair Value of Plan Assets (Period End)	0.0	0.0
Level 1 \| Fixed income securities
Fair value assets and liabilities measured on recurring basis
Fair Value of Plan Assets (Period Start)	19.6
Fair Value of Plan Assets (Period End)	22.7	19.6
Level 1 \| Insurance contracts
Fair value assets and liabilities measured on recurring basis
Fair Value of Plan Assets (Period Start)	0.0
Fair Value of Plan Assets (Period End)	0.0	0.0
Level 1 \| Other plan assets
Fair value assets and liabilities measured on recurring basis
Fair Value of Plan Assets (Period Start)	27.8
Fair Value of Plan Assets (Period End)	28.9	27.8
Level 1 \| Total plan assets subject to leveling
Fair value assets and liabilities measured on recurring basis
Fair Value of Plan Assets (Period Start)	65.4
Fair Value of Plan Assets (Period End)	70.9	65.4
Level 2 \| Investment funds
Fair value assets and liabilities measured on recurring basis
Fair Value of Plan Assets (Period Start)	0.0
Fair Value of Plan Assets (Period End)	0.0	0.0
Level 2 \| Limited partnerships
Fair value assets and liabilities measured on recurring basis
Fair Value of Plan Assets (Period Start)	0.0
Fair Value of Plan Assets (Period End)	0.0	0.0
Level 2 \| Fixed income securities
Fair value assets and liabilities measured on recurring basis
Fair Value of Plan Assets (Period Start)	0.0
Fair Value of Plan Assets (Period End)	0.0	0.0
Level 2 \| Insurance contracts
Fair value assets and liabilities measured on recurring basis
Fair Value of Plan Assets (Period Start)	5.5
Fair Value of Plan Assets (Period End)	3.6	5.5
Level 2 \| Other plan assets
Fair value assets and liabilities measured on recurring basis
Fair Value of Plan Assets (Period Start)	0.0
Fair Value of Plan Assets (Period End)	0.0	0.0
Level 2 \| Total plan assets subject to leveling
Fair value assets and liabilities measured on recurring basis
Fair Value of Plan Assets (Period Start)	5.5
Fair Value of Plan Assets (Period End)	3.6	5.5
Level 3 \| Investment funds
Fair value assets and liabilities measured on recurring basis
Fair Value of Plan Assets (Period Start)	0.0
Fair Value of Plan Assets (Period End)	0.0	0.0
Level 3 \| Limited partnerships
Fair value assets and liabilities measured on recurring basis
Fair Value of Plan Assets (Period Start)	25.6	25.6
Actual return on plan assets	0.3	0.0
Fair Value of Plan Assets (Period End)	25.9	25.6
Level 3 \| Fixed income securities
Fair value assets and liabilities measured on recurring basis
Fair Value of Plan Assets (Period Start)	0.0
Fair Value of Plan Assets (Period End)	0.0	0.0
Level 3 \| Insurance contracts
Fair value assets and liabilities measured on recurring basis
Fair Value of Plan Assets (Period Start)	0.0
Fair Value of Plan Assets (Period End)	0.0	0.0
Level 3 \| Other plan assets
Fair value assets and liabilities measured on recurring basis
Fair Value of Plan Assets (Period Start)	0.0
Fair Value of Plan Assets (Period End)	0.0	0.0
Level 3 \| Total plan assets subject to leveling
Fair value assets and liabilities measured on recurring basis
Fair Value of Plan Assets (Period Start)	25.6
Fair Value of Plan Assets (Period End)	$ 25.9	$ 25.6

Employee Benefits Allocation of Plan Assets (Details)	Dec. 31, 2020	Dec. 31, 2019
Allocation of Plan Assets
Defined benefit plan, plan assets, target allocation, percentage	100.00%
Defined benefit plan, actual plan asset allocations	100.00%	100.00%
Alternative Investments
Allocation of Plan Assets
Defined benefit plan, plan assets, target allocation, percentage	23.00%
Defined benefit plan, actual plan asset allocations	24.00%	25.00%
Equity securities
Allocation of Plan Assets
Defined benefit plan, plan assets, target allocation, percentage	27.00%
Defined benefit plan, actual plan asset allocations	27.00%	25.00%
Fixed income securities
Allocation of Plan Assets
Defined benefit plan, plan assets, target allocation, percentage	19.00%
Defined benefit plan, actual plan asset allocations	18.00%	19.00%
Liability driven investments
Allocation of Plan Assets
Defined benefit plan, plan assets, target allocation, percentage	15.00%
Defined benefit plan, actual plan asset allocations	15.00%	14.00%
Real estate
Allocation of Plan Assets
Defined benefit plan, plan assets, target allocation, percentage	9.00%
Defined benefit plan, actual plan asset allocations	9.00%	9.00%
Other plan assets
Allocation of Plan Assets
Defined benefit plan, plan assets, target allocation, percentage	7.00%
Defined benefit plan, actual plan asset allocations	7.00%	8.00%

Pension Cash Flows (Details) - USD ($) $ in Millions	12 Months Ended
Pension Cash Flows (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Defined Benefit Plans and Other Postretirement Benefit Plans
Estimated U.S. federal subsidies expected to be received under the Medicare Prescription Drug, Improvement and Modernization Act of 2003, no more than	$ 0.2
Domestic Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans
Employer contributions	1.3	$ 2.4
Defined benefit plan, estimated future employer contributions in next fiscal year	3.0
Defined Benefit Plan, Expected Future Benefit Payments, Fiscal Year Maturity
Expected future benefit payments in 2019	10.2
Expected future benefit payments in 2020	8.0
Expected future benefit payments in 2021	7.5
Expected future benefit payments in 2022	7.5
Expected future benefit payments in 2023	7.4
Expected future benefit payments in 2024-2025	34.2
Foreign Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans
Employer contributions	18.4	18.0
Defined benefit plan, estimated future employer contributions in next fiscal year	19.0
Defined Benefit Plan, Expected Future Benefit Payments, Fiscal Year Maturity
Expected future benefit payments in 2019	25.0
Expected future benefit payments in 2020	22.9
Expected future benefit payments in 2021	24.0
Expected future benefit payments in 2022	25.2
Expected future benefit payments in 2023	25.9
Expected future benefit payments in 2024-2025	129.5
Other Postretirement Benefits Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans
Employer contributions	3.1	$ 3.4
Defined Benefit Plan, Expected Future Benefit Payments, Fiscal Year Maturity
Expected future benefit payments in 2019	2.5
Expected future benefit payments in 2020	2.3
Expected future benefit payments in 2021	2.1
Expected future benefit payments in 2022	2.0
Expected future benefit payments in 2023	1.8
Expected future benefit payments in 2024-2025	$ 8.0

Savings Plans (Details) - USD ($) $ in Millions	12 Months Ended
Savings Plans (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Domestic Tax Authority
Defined Benefit Plans and Other Postretirement Benefit Plans
Cost Recognized	$ 58.7	$ 61.2	$ 52.6
Discretionary Company Contribution
Defined Benefit Plans and Other Postretirement Benefit Plans
Cost Recognized	2.9	8.1	6.7
Defined Contribution Plans Participant Forfeitures
Defined Benefit Plans and Other Postretirement Benefit Plans
Cost Recognized	5.1	5.6	5.8
Foreign Tax Authority
Defined Benefit Plans and Other Postretirement Benefit Plans
Cost Recognized	$ 46.3	$ 54.5	$ 51.3

Segment Operations (Details) $ in Millions	3 Months Ended								12 Months Ended
Segment Operations (Details) $ in Millions	Dec. 31, 2020 USD ($)	Sep. 30, 2020 USD ($)	Jun. 30, 2020 USD ($)	Mar. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)	Sep. 30, 2019 USD ($)	Jun. 30, 2019 USD ($)	Mar. 31, 2019 USD ($)	Dec. 31, 2020 USD ($) numberOfPeople	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)
Segments:
Number of Reportable Segments \| numberOfPeople									2
EBITA									$ 674.3	$ 1,172.0	$ 1,046.4
Total (expenses) and other income	$ (49.8)	$ (56.0)	$ (65.4)	$ (55.9)	$ (63.5)	$ (47.6)	$ (47.7)	$ (48.9)	(227.1)	(207.7)	(170.8)
Total revenue	2,550.0	2,125.5	2,025.7	2,359.8	2,901.8	2,438.1	2,520.2	2,361.2	9,061.0	10,221.3	9,714.4
Net revenue	2,284.4	1,954.6	1,853.4	1,972.1	2,433.0	2,061.4	2,125.9	2,004.8	8,064.5	8,625.1	8,031.6
Operating Income (Loss)	223.4	248.6	40.5	75.9	491.3	280.3	264.2	50.2	588.4	1,086.0	1,008.8
Amortization of Intangible Assets									85.9	86.0	37.6
Interest expense									(192.2)	(199.3)	(123.0)
Interest income									29.5	34.5	21.8
Other expense, net	(9.8)	$ (11.3)	$ (21.5)	$ (21.8)	(24.8)	$ (7.4)	$ (3.8)	$ (6.9)	(64.4)	(42.9)	(69.6)
Income before income taxes									361.3	878.3	838.0
Depreciation and amortization									204.7	192.5	165.3
Capital expenditures									167.5	198.5	177.1
Assets	18,042.7				17,751.9				18,042.7	17,751.9
IAN
Segments:
EBITA									699.1	1,115.7	1,038.8
Total revenue									7,410.1	7,992.0	7,427.3
Net revenue									6,921.4	7,328.8	6,720.9
Amortization of Intangible Assets									81.5	81.6	32.2
Depreciation and amortization									178.9	164.6	136.0
Capital expenditures									132.0	161.8	143.7
Assets	14,784.5				15,155.2				14,784.5	15,155.2
DXTRA
Segments:
EBITA									56.5	158.1	183.6
Total revenue									1,650.9	2,229.3	2,287.1
Net revenue									1,143.1	1,296.3	1,310.7
Amortization of Intangible Assets									4.4	4.4	5.4
Depreciation and amortization									20.4	20.6	19.8
Capital expenditures									8.4	13.3	13.2
Assets	1,549.2				1,725.5				1,549.2	1,725.5
Corporate and Other
Segments:
EBITA									(81.3)	(101.8)	(176.0)
Amortization of Intangible Assets									0.0	0.0	0.0
Depreciation and amortization									5.4	7.3	9.5
Capital expenditures									27.1	23.4	$ 20.2
Assets	$ 1,709.0				$ 871.2				$ 1,709.0	$ 871.2

Segment Information Major Geographic Area (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Revenues and Long-Lived Assets
Long-Lived Assets	$ 2,494.0				$ 2,843.8				$ 2,494.0	$ 2,843.8
Net revenue	2,284.4	$ 1,954.6	$ 1,853.4	$ 1,972.1	2,433.0	$ 2,061.4	$ 2,125.9	$ 2,004.8	8,064.5	8,625.1	$ 8,031.6
Domestic
Revenues and Long-Lived Assets
Long-Lived Assets	1,801.4				2,080.4				1,801.4	2,080.4
Total International
Revenues and Long-Lived Assets
Long-Lived Assets	692.6				763.4				692.6	763.4
Net revenue									2,853.1	3,239.0	3,206.6
United Kingdom
Revenues and Long-Lived Assets
Long-Lived Assets	216.6				167.6				216.6	167.6
Net revenue									664.3	727.0	711.7
Continental Europe
Revenues and Long-Lived Assets
Long-Lived Assets	117.5				149.7				117.5	149.7
Net revenue									683.6	742.4	737.5
Asia Pacific
Revenues and Long-Lived Assets
Long-Lived Assets	183.1				240.9				183.1	240.9
Net revenue									710.5	858.3	896.8
Latin America
Revenues and Long-Lived Assets
Long-Lived Assets	58.9				74.8				58.9	74.8
Net revenue									323.4	389.9	350.1
Other
Revenues and Long-Lived Assets
Long-Lived Assets	$ 116.5				$ 130.4				116.5	130.4
Net revenue									$ 471.3	$ 521.4	$ 510.5

Guarantees (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Commitments and Contingencies Disclosure [Abstract]
Parent company guarantees on lease obligations	$ 630.8	$ 739.1
Parent company guarantees relating to credit facilities	399.6	293.8
Cash pooling guarantees	109.2	$ 207.7
Assets pledged as security for parent company guarantees	$ 0.0

Contingent Acquisition Obligations (Details) $ in Millions	Dec. 31, 2020 USD ($)
Deferred acquisition payments
Business Acquisition, Contingent Consideration [Line Items]
Future contingent acquisition obligation due in 2018	$ 47.9
Future contingent acquisition obligation due in 2019	10.9
Future contingent acquisition obligation due in 2020	7.0
Future contingent acquisition obligation due in 2021	8.4
Future contingent acquisition obligation due in 2022	0.0
Future contingent acquisition obligation due thereafter	2.9
Future contingent acquisition obligation due, total	77.1
Redeemable noncontrolling interests and call options with affiliates
Business Acquisition, Contingent Consideration [Line Items]
Future contingent acquisition obligation due in 2018	17.2
Future contingent acquisition obligation due in 2019	23.3
Future contingent acquisition obligation due in 2020	26.8
Future contingent acquisition obligation due in 2021	1.5
Future contingent acquisition obligation due in 2022	0.7
Future contingent acquisition obligation due thereafter	0.0
Future contingent acquisition obligation due, total	69.5
Redeemable at noncontrolling equity owners discretion
Business Acquisition, Contingent Consideration [Line Items]
Future contingent acquisition obligation due in 2018	14.2
Total contingent acquisition payments
Business Acquisition, Contingent Consideration [Line Items]
Future contingent acquisition obligation due in 2018	65.1
Future contingent acquisition obligation due in 2019	34.2
Future contingent acquisition obligation due in 2020	33.8
Future contingent acquisition obligation due in 2021	9.9
Future contingent acquisition obligation due in 2022	0.7
Future contingent acquisition obligation due thereafter	2.9
Future contingent acquisition obligation due, total	$ 146.6

Results by Quarter (Unaudited) (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Quarterly Financial Information Disclosure [Abstract]
Net revenue	$ 2,284.4	$ 1,954.6	$ 1,853.4	$ 1,972.1	$ 2,433.0	$ 2,061.4	$ 2,125.9	$ 2,004.8	$ 8,064.5	$ 8,625.1	$ 8,031.6
Billable expenses	265.6	170.9	172.3	387.7	468.8	376.7	394.3	356.4	996.5	1,596.2	1,682.8
Total revenue	2,550.0	2,125.5	2,025.7	2,359.8	2,901.8	2,438.1	2,520.2	2,361.2	9,061.0	10,221.3	9,714.4
Salaries and related expenses	1,346.2	1,269.9	1,306.1	1,422.8	1,432.1	1,334.4	1,381.2	1,421.1	5,345.0	5,568.8	5,298.3
Office and other direct expenses	364.8	307.9	317.0	378.2	419.7	367.9	387.3	389.2	1,367.9	1,564.1	1,355.1
Billable expense	265.6	170.9	172.3	387.7	468.8	376.7	394.3	356.4	996.5	1,596.2	1,682.8
Cost of services	1,976.6	1,748.7	1,795.4	2,188.7	2,320.6	2,079.0	2,162.8	2,166.7	7,709.4	8,729.1	8,336.2
Depreciation and amortization	73.7	71.0	73.1	72.8	65.4	69.0	73.0	71.1	290.6	278.5	202.9
Restructuring Charges	253.9	47.3	112.6	0.0	0.0	0.0	2.1	31.8	413.8	33.9	0.0
Total operating expenses	2,326.6	1,876.9	1,985.2	2,283.9	2,410.5	2,157.8	2,256.0	2,311.0	8,472.6	9,135.3	8,705.6
Operating Income (Loss)	223.4	248.6	40.5	75.9	491.3	280.3	264.2	50.2	588.4	1,086.0	1,008.8
Interest Income (Expense), Nonoperating, Net	(40.0)	(44.7)	(43.9)	(34.1)	(38.7)	(40.2)	(43.9)	(42.0)
Net losses on sales of businesses	15.2	8.6	19.9	23.3	23.9	7.7	3.2	8.6	(67.0)	(43.4)	(61.9)
Tax Adjustments, Settlements, and Unusual Provisions		136.2					13.9		(136.2)	0.0	0.0
reversal of valuation allowance					25.3
Total (expenses) and other income	(49.8)	(56.0)	(65.4)	(55.9)	(63.5)	(47.6)	(47.7)	(48.9)	(227.1)	(207.7)	(170.8)
Various Discrete Tax Items		(3.2)	(10.4)
NET INCOME	117.0	278.5	(43.9)	2.6	342.2	168.4	172.8	(9.5)	$ 354.2	$ 673.9	$ 637.7
Net income available to IPG common stockholders	$ 112.3	$ 279.7	$ (45.6)	$ 4.7	$ 328.9	$ 165.6	$ 169.5	$ (8.0)
Earnings per share, Basic	$ 0.29	$ 0.72	$ (0.12)	$ 0.01	$ 0.85	$ 0.43	$ 0.44	$ (0.02)	$ 0.90	$ 1.70	$ 1.61
Earnings per share, Diluted	0.28	0.71	(0.12)	0.01	0.84	0.42	0.43	(0.02)	$ 0.89	$ 1.68	$ 1.59
Dividends declared per common share	$ 0.255	$ 0.255	$ 0.255	$ 0.255	$ 0.235	$ 0.235	$ 0.235	$ 0.235

Subsequent Events (Details)	Feb. 10, 2021 $ / shares
Subsequent Event [Member]
Subsequent Event [Line Items]
Dividends payable, amount per share	$ 0.27