Consolidated Statements of Stockholders' Equity - USD ($) shares in Millions, $ in Millions	Total	Preferred Stock	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
Balance at Dec. 31, 2012	$ 2,456.6	$ 221.5	$ 48.8	$ 2,465.4	$ 738.3	$ (288.0)	$ (765.4)	$ 2,420.6	$ 36.0
Balance, shares at Dec. 31, 2012			492.0
Net income	288.9				267.9			267.9	21.0
Other comprehensive loss	(127.1)					(123.2)		(123.2)	(3.9)
Reclassifications related to redeemable noncontrolling interests	(4.4)			0.2				0.2	(4.6)
Noncontrolling interest transactions	1.0			(0.1)				(0.1)	1.1
Distributions to noncontrolling interests	(14.9)								(14.9)
Change in redemption value of redeemable noncontrolling interests	(6.2)				(6.2)			(6.2)
Repurchase of common stock	(481.8)						(481.8)	(481.8)
Common stock dividends	(126.0)				(126.0)			(126.0)
Preferred stock dividends	(8.7)				(8.7)			(8.7)
Conversion of convertible notes to common stock, shares			16.9
Conversion of convertible notes to common stock	200.0		$ 1.7	198.3				200.0
Capped call transaction	0.0			19.1			(19.1)	0.0
Conversion of preferred stock to common stock, shares		(221.5)	17.3
Conversion of preferred stock to common stock	0.0		$ 1.7	219.8				0.0
Stock-based compensation, shares			2.4
Stock-based compensation, Value	43.6		$ 0.5	43.1				43.6
Exercise of stock options, shares			5.2
Exercise of stock options, Value	47.9		$ 0.5	47.4				47.9
Shares withheld for taxes, shares			(1.5)
Shares withheld for taxes, Value	(20.1)		$ (0.2)	(19.9)				(20.1)
Other	2.0			1.9	(0.8)			1.1	0.9
Balance, shares at Dec. 31, 2013			532.3
Balance at Dec. 31, 2013	2,250.8	$ 0.0	$ 53.0	2,975.2	864.5	(411.2)	(1,266.3)	2,215.2	35.6
Net income	505.4				477.1			477.1	28.3
Other comprehensive loss	(228.1)					(225.5)		(225.5)	(2.6)
Reclassifications related to redeemable noncontrolling interests	(7.7)			(3.5)				(3.5)	(4.2)
Noncontrolling interest transactions	(2.3)			2.1				2.1	(4.4)
Distributions to noncontrolling interests	(17.0)								(17.0)
Change in redemption value of redeemable noncontrolling interests	1.5				1.5			1.5
Repurchase of common stock	(275.1)						(275.1)	(275.1)
Retirement of treasury stock, shares			(121.9)
Retirement of treasury stock	0.0		$ (12.2)	(1,510.2)			1,522.4	0.0
Common stock dividends	(159.0)				(159.0)			(159.0)
Stock-based compensation, shares			3.4
Stock-based compensation, Value	63.8		$ 0.3	63.5				63.8
Exercise of stock options, shares			1.7
Exercise of stock options, Value	20.3		$ 0.2	20.1				20.3
Shares withheld for taxes, shares			(0.9)
Shares withheld for taxes, Value	(15.0)		$ (0.1)	(14.9)				(15.0)
Excess tax benefit from stock-based compensation	15.2			15.2				15.2
Other	(1.6)				(0.8)			(0.8)	(0.8)
Balance, shares at Dec. 31, 2014			414.6
Balance at Dec. 31, 2014	2,151.2	0.0	$ 41.2	1,547.5	1,183.3	(636.7)	(19.0)	2,116.3	34.9
Net income	480.5				454.6			454.6	25.9
Other comprehensive loss	(213.1)					(208.9)		(208.9)	(4.2)
Reclassifications related to redeemable noncontrolling interests	(6.0)								(6.0)
Noncontrolling interest transactions	1.2								1.2
Distributions to noncontrolling interests	(15.9)								(15.9)
Change in redemption value of redeemable noncontrolling interests	(3.9)				(3.9)			(3.9)
Repurchase of common stock	(285.2)						(285.2)	(285.2)
Retirement of treasury stock, shares			(11.3)
Retirement of treasury stock	0.0		$ (1.2)	(232.0)			233.2	0.0
Common stock dividends	(195.5)				(195.5)			(195.5)
Stock-based compensation, shares			2.5
Stock-based compensation, Value	83.4		$ 0.3	83.1				83.4
Exercise of stock options, shares			1.3
Exercise of stock options, Value	13.7		$ 0.2	13.5				13.7
Shares withheld for taxes, shares			(0.8)
Shares withheld for taxes, Value	(17.8)		$ (0.1)	(17.7)				(17.8)
Excess tax benefit from stock-based compensation	10.2			10.2				10.2
Other	(1.0)			(0.5)	(0.9)			(1.4)	0.4
Balance, shares at Dec. 31, 2015			406.3
Balance at Dec. 31, 2015	$ 2,001.8	$ 0.0	$ 40.4	$ 1,404.1	$ 1,437.6	$ (845.6)	$ (71.0)	$ 1,965.5	$ 36.3