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	9.1		9.1
Stock-based compensation and additional related tax benefits	24.8		25.8	(1.0)
Treasury stock acquired, common	(64.2)					(64.2)
Dividends to common stockholders	(54.3)			(54.3)
Dividends to preferred stockholders	(8.2)			(8.2)
Distributions to noncontrolling interest	(3.2)						(3.2)
Contributions from noncontrolling interest	4.2						4.2
Net income (loss) (excludes $0.1 million and $0.2 million attributable to redeemable noncontrolling interest in 2013 and 2012)	221.1			212.1			9.0
Other comprehensive income (loss) (excludes $(1.0) million and $0.7 million attributable to redeemable noncontrolling interest in 2013 and 2012)	224.5				224.4		0.1
Balances at Mar. 31, 2012	9,660.0	4.5	9,669.6	4,472.0	495.8	(5,345.9)	363.9	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	20.3	0.1	20.2
Stock-based compensation and additional related tax benefits	19.4		20.4	(1.0)
Treasury stock acquired, common	(90.9)					(90.9)
Dividends to common stockholders	(67.6)			(67.6)
Dividends to preferred stockholders	(8.2)			(8.2)
Distributions to noncontrolling interest	(3.6)						(3.6)
Contributions from noncontrolling interest	113.9						113.9
Purchase of subsidiary shares from noncontrolling interest	(30.6)						(30.6)
Net income (loss) (excludes $0.1 million and $0.2 million attributable to redeemable noncontrolling interest in 2013 and 2012)	189.9			186.5			3.4
Other comprehensive income (loss) (excludes $(1.0) million and $0.7 million attributable to redeemable noncontrolling interest in 2013 and 2012)	(19.4)				(19.3)		(0.1)
Balances at Mar. 31, 2013	$ 9,826.6	$ 4.6	$ 9,771.5	$ 4,971.7	$ 621.0	$ (5,645.3)	$ 103.0	$ 0	$ 0.1