Consolidated Statements of Stockholders' Equity (USD $) In Millions	Total	Preferred Stock	Common Stock	Additional Paid-In Capital	Retained Earnings	Accumulated Other Comprehensive Loss, Net of Tax	Treasury Stock	Total IPG Stockholders' Equity	Noncontrolling Interests
Beginning balance at Dec. 31, 2011	$ 2,497.3	$ 221.5	$ 48.2	$ 2,427.5	$ 405.1	$ (225.7)	$ (414.9)	$ 2,461.7	$ 35.6
Beginning balance, shares at Dec. 31, 2011			491.4
Net income	59.8				58.9			58.9	0.9
Other comprehensive (loss) income	56.3					57.4		57.4	(1.1)
Reclassifications related to redeemable noncontrolling interests	15.7			12.0				12.0	3.7
Noncontrolling interest transactions	(0.8)								(0.8)
Distributions to noncontrolling interests	(9.0)								(9.0)
Change in redemption value of redeemable noncontrolling interests	3.1				3.1			3.1
Repurchase of common stock	(118.1)						(118.1)	(118.1)
Common stock dividends	(52.3)				(52.3)			(52.3)
Preferred stock dividends	(5.8)				(5.8)			(5.8)
Stock-based compensation, shares			1.7
Stock-based compensation	21.4		0.6	20.8				21.4
Exercise of stock options, shares			0.8
Exercise of stock options	7.8		0.1	7.7				7.8
Shares withheld for taxes, shares			(2.0)
Shares withheld for taxes	(23.1)		(0.2)	(22.9)				(23.1)
Other	0.1			1.8	(0.8)			1.0	(0.9)
Ending balance at Jun. 30, 2012	2,452.4	221.5	48.7	2,446.9	408.2	(168.3)	(533.0)	2,424.0	28.4
Ending balance, shares at Jun. 30, 2012			491.9
Beginning 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
Beginning balance, shares at Dec. 31, 2012			492.0
Net income	27.6				26.5			26.5	1.1
Other comprehensive (loss) income	(110.4)					(107.4)		(107.4)	(3.0)
Reclassifications related to redeemable noncontrolling interests	3.6								3.6
Distributions to noncontrolling interests	(7.0)								(7.0)
Change in redemption value of redeemable noncontrolling interests	0.6				0.6			0.6
Repurchase of common stock	(180.6)						(180.6)	(180.6)
Common stock dividends	(62.7)				(62.7)			(62.7)
Preferred stock dividends	(5.8)				(5.8)			(5.8)
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			19.1			(19.1)	0
Stock-based compensation, shares			2.4
Stock-based compensation	32.5		0.4	32.1				32.5
Exercise of stock options, shares			3.5
Exercise of stock options	31.9		0.4	31.5				31.9
Shares withheld for taxes, shares			(1.5)
Shares withheld for taxes	(19.6)		(0.2)	(19.4)				(19.6)
Excess tax benefit from stock-based compensation	6.8			6.8				6.8
Other	2.9			1.9	(0.4)			1.5	1.4
Ending balance at Jun. 30, 2013	$ 2,376.4	$ 221.5	$ 51.1	$ 2,735.7	$ 696.5	$ (395.4)	$ (965.1)	$ 2,344.3	$ 32.1
Ending balance, shares at Jun. 30, 2013			513.3