Consolidated Statements of Stockholders' Equity - USD ($) shares in Millions, $ in Millions	Total	Common Stock, Shares	Common Stock, Amount	Additional Paid-In Capital	Retained Earnings	Accumulated Other Comprehensive Loss, Net of Tax	Treasury Stock	Total IPG Stockholders' Equity	Noncontrolling Interests
Balance at Dec. 31, 2014	$ 2,151.2		$ 41.2	$ 1,547.5	$ 1,183.3	$ (636.7)	$ (19.0)	$ 2,116.3	$ 34.9
Balance, Common Stock Shares at Dec. 31, 2014		414.6
Net income (loss)	(4.2)				(1.8)
Income (Loss) Attributable to Parent								(1.8)
Net Income (Loss) Attributable to Noncontrolling Interest	(2.4)								(2.4)
Other comprehensive income (loss)	(128.8)					(128.0)		(128.0)
Other Comprehensive Income (Loss), Attributable to Noncontrolling Interest									(0.8)
Reclassifications related to redeemable noncontrolling interests	1.5								1.5
Distributions to noncontrolling interests	(1.2)								(1.2)
Change in redemption value of redeemable noncontrolling interests	(5.8)				(5.8)			(5.8)
Repurchase of common stock	(51.2)						(51.2)	(51.2)
Common stock dividends	(49.3)				(49.3)			(49.3)
Stock-based compensation, shares		2.2
Stock-based compensation, value	32.0		0.2	31.8				32.0
Exercise of stock options, shares		0.9
Exercise of stock options, value	9.2		0.1	9.1				9.2
Shares withheld for taxes, shares		(0.8)
Shares withheld for taxes, value	(17.1)		(0.1)	(17.0)				(17.1)
Excess tax benefit from stock-based compensation	8.5			8.5				8.5
Other	(0.1)			0.1	(0.2)			(0.1)
Balance at Mar. 31, 2015	1,944.7		41.4	1,580.0	1,126.2	(764.7)	(70.2)	1,912.7	32.0
Balance, Common Stock Shares at Mar. 31, 2015		416.9
Balance at Dec. 31, 2015	2,001.8		40.4	1,404.1	1,437.6	(845.6)	(71.0)	1,965.5	36.3
Balance, Common Stock Shares at Dec. 31, 2015		406.3
Net income (loss)	2.7				5.4
Income (Loss) Attributable to Parent								5.4
Net Income (Loss) Attributable to Noncontrolling Interest	(2.7)								(2.7)
Other comprehensive income (loss)	58.6					58.1		58.1
Other Comprehensive Income (Loss), Attributable to Noncontrolling Interest									0.5
Reclassifications related to redeemable noncontrolling interests	2.9								2.9
Distributions to noncontrolling interests	(4.0)								(4.0)
Change in redemption value of redeemable noncontrolling interests	(3.8)				(3.8)			(3.8)
Repurchase of common stock	(53.7)						(53.7)	(53.7)
Common stock dividends	(59.9)				(59.9)			(59.9)
Stock-based compensation, shares		3.4
Stock-based compensation, value	48.0		0.3	47.7				48.0
Exercise of stock options, shares		0.5
Exercise of stock options, value	4.0		0.1	3.9				4.0
Shares withheld for taxes, shares		(1.0)
Shares withheld for taxes, value	(22.3)		(0.1)	(22.2)				(22.3)
Other	(0.4)			0.5	(0.3)			0.2	(0.6)
Balance at Mar. 31, 2016	$ 1,973.9		$ 40.7	$ 1,434.0	$ 1,379.0	$ (787.5)	$ (124.7)	$ 1,941.5	$ 32.4
Balance, Common Stock Shares at Mar. 31, 2016			409.2