Consolidated Statements of Stockholders' Equity (USD $) In Millions, unless otherwise specified	Total	Common stock	Additional paid-in capital	Retained earnings (accumulated deficit)	Accumulated other comprehensive income (loss)	Treasury stock	Noncontrolling interest	Series A Preferred stock	Series B Preferred stock
Balances at Dec. 31, 2011	$ 9,306.2	$ 4.5	$ 9,634.7	$ 4,323.4	$ 271.4	$ (5,281.7)	$ 353.8	$ 0	$ 0.1
Increase (decrease) in stockholders' equity
Common stock issued	11.7		11.7
Stock-based compensation and additional related tax benefits	37.2		39.0	(1.8)
Treasury stock acquired, common	(203.2)					(203.2)
Dividends to common stockholders	(108.0)			(108.0)
Dividends to preferred stockholders	(16.5)			(16.5)
Distributions to noncontrolling interest	(5.7)						(5.7)
Contributions from noncontrolling interest	6.2						6.2
Deconsolidation of certain variable interest entities	(353.2)						(353.2)
Net income (loss) (excludes $1.1 million and $0.7 million attributable to redeemable noncontrolling interest in 2013 and 2012)	399.2			388.0			11.2
Other comprehensive income (loss) (excludes $(4.0) million and $0.3 million attributable to redeemable noncontrolling interest in 2013 and 2012)	289.9				290.0		(0.1)
Balances at Jun. 30, 2012	9,363.8	4.5	9,685.4	4,585.1	561.4	(5,484.9)	12.2	0	0.1
Balances at Dec. 31, 2012	9,703.4	4.5	9,730.9	4,862.0	640.3	(5,554.4)	20.0	0	0.1
Increase (decrease) in stockholders' equity
Common stock issued	37.8	0.1	37.7
Stock-based compensation and additional related tax benefits	35.9		38.1	(2.2)
Treasury stock acquired, common	(91.4)					(91.4)
Dividends to common stockholders	(135.2)			(135.2)
Dividends to preferred stockholders	(16.5)			(16.5)
Distributions to noncontrolling interest	(6.4)						(6.4)
Contributions from noncontrolling interest	115.9						115.9
Purchase of subsidiary shares from noncontrolling interest	(45.6)		1.6				(47.2)
Sale of subsidiary shares to noncontrolling interest	31.8		11.5				20.3
Net income (loss) (excludes $1.1 million and $0.7 million attributable to redeemable noncontrolling interest in 2013 and 2012)	425.5			417.1			8.4
Other comprehensive income (loss) (excludes $(4.0) million and $0.3 million attributable to redeemable noncontrolling interest in 2013 and 2012)	(646.3)				(640.8)		(5.5)
Balances at Jun. 30, 2013	$ 9,408.9	$ 4.6	$ 9,819.8	$ 5,125.2	$ (0.5)	$ (5,645.8)	$ 105.5	$ 0	$ 0.1