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	127.5				130.5			130.5	(3.0)
Other comprehensive income (loss)	67.6					68.1		68.1	(0.5)
Reclassifications related to redeemable noncontrolling interests	20.3			12.0				12.0	8.3
Noncontrolling interest transactions	(1.3)								(1.3)
Distributions to noncontrolling interests	(12.2)								(12.2)
Change in redemption value of redeemable noncontrolling interests	3.1				3.1			3.1
Repurchase of common stock	(201.4)						(201.4)	(201.4)
Common stock dividends	(78.1)				(78.1)			(78.1)
Preferred stock dividends	(8.7)				(8.7)			(8.7)
Stock-based compensation, shares			1.8
Stock-based compensation	26.5		0.7	25.8				26.5
Exercise of stock options, shares			0.9
Exercise of stock options	8.6		0.1	8.5				8.6
Shares withheld for taxes, shares			(2.1)
Shares withheld for taxes	(23.5)		(0.2)	(23.3)				(23.5)
Other	0.8			(2.0)	(1.0)			(3.0)	3.8
Ending balance at Sep. 30, 2012	2,426.5	221.5	48.8	2,448.5	450.9	(157.6)	(616.3)	2,395.8	30.7
Ending balance, shares at Sep. 30, 2012			492.0
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	76.8				74.8			74.8	2.0
Other comprehensive income (loss)	(84.5)					(81.3)		(81.3)	(3.2)
Reclassifications related to redeemable noncontrolling interests	4.9								4.9
Distributions to noncontrolling interests	(10.4)								(10.4)
Change in redemption value of redeemable noncontrolling interests	0.6				0.6			0.6
Repurchase of common stock	(280.8)						(280.8)	(280.8)
Common stock dividends	(94.1)				(94.1)			(94.1)
Preferred stock dividends	(8.7)				(8.7)			(8.7)
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	37.6		0.4	37.2				37.6
Exercise of stock options, shares			4.7
Exercise of stock options	44.1		0.5	43.6				44.1
Shares withheld for taxes, shares			(1.5)
Shares withheld for taxes	(20.0)		(0.2)	(19.8)				(20.0)
Excess tax benefit from stock-based compensation	8.5			8.5				8.5
Other	2.9			1.8	(0.5)			1.3	1.6
Ending balance at Sep. 30, 2013	$ 2,333.5	$ 221.5	$ 51.2	$ 2,754.1	$ 710.4	$ (369.3)	$ (1,065.3)	$ 2,302.6	$ 30.9
Ending balance, shares at Sep. 30, 2013			514.5