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
Common stock, shares issued		394.3
Balance at Dec. 31, 2016	$ 2,090.4		$ 39.4	$ 1,199.2	$ 1,839.9	$ (964.4)	$ (63.3)	$ 2,050.8	$ 39.6
Cumulative effect of accounting change	570.4
Net Income (Loss) Attributable to Parent	554.4
NET INCOME	570.4				554.4			554.4
Net Income (Loss) Attributable to Nonredeemable Noncontrolling Interest	16.0								16.0
Other comprehensive income	138.1					136.6		136.6	1.5
Reclassifications related to redeemable noncontrolling interests	0.6			(0.3)				(0.3)	0.9
Distributions to noncontrolling interests	(20.9)								(20.9)
Change in redemption value of RNCI	(7.9)				(7.9)			(7.9)
Repurchases of common stock	(300.1)						(300.1)	300.1
Retirement of treasury stock, shares			(13.4)
Retirement of treasury stock	(0.0)		$ (1.3)	(303.1)			(304.4)	(0.0)
Common stock dividends	(280.3)				(280.3)			(280.3)
Stock-based compensation, shares			5.7
Shares Issued, Value, Share-based Payment Arrangement, after Forfeiture	87.0		$ 0.6	86.4				87.0
Exercise of stock options, shares			1.2
Exercise of stock options, Value	13.2		$ 0.1	13.1				13.2
Shares withheld for taxes, shares			(1.6)
Shares withheld for taxes, value	39.0		$ 0.2	38.8				39.0
Other	(5.2)			1.3	(1.6)			(2.9)	(2.3)
Balance at Dec. 31, 2017	2,246.3		$ 38.6	955.2	2,104.5	(827.8)	(59.0)	2,211.5	34.8
Common stock, shares issued		386.2
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
Common stock, shares issued	383.6	383.6
Cumulative effect of accounting change	$ 1.2				1.2			1.2
Net Income (Loss) Attributable to Parent	656.0				656.0			656.0
NET INCOME	673.9
Net Income (Loss) Attributable to Nonredeemable Noncontrolling Interest	17.9								17.9
Other comprehensive income	10.4					11.1		11.1
Other Comprehensive Income (Loss), Tax, Portion Attributable to Noncontrolling Interest									(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
APIC, Share-based Payment Arrangement, Increase for Cost Recognition	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)		$ 2,775.9	$ 49.7
Common stock, shares issued	387.0	387.0