Consolidated Statements of Stockholders' Equity (USD $) In Millions, unless otherwise specified	Series A Preferred stock	Series B Preferred stock	Common stock	Additional paid-in capital	Retained earnings (accumulated deficit)	Accumulated other comprehensive income (loss)	Treasury stock	Noncontrolling interest	Total
Balances at Dec. 31, 2013	$ 0.0	$ 0.1	$ 4.6	$ 9,798.9	$ 5,405.4	$ 183.2	$ (5,708.0)	$ 92.8	$ 9,777.0
Increase (decrease) in stockholders' equity
Common stock issued				16.1					16.1
Stock-based compensation and additional related tax benefits				22.7	(1.4)				21.3
Treasury stock acquired, common							(89.0)		(89.0)
Dividends to common stockholders					(82.7)				(82.7)
Dividends to preferred stockholders					(8.2)				(8.2)
Distributions to noncontrolling interest								(22.0)	(22.0)
Contributions from noncontrolling interest								7.9	7.9
Purchase of subsidiary shares from noncontrolling interest								(25.3)	(25.3)
Adjustments to redemption amount of redeemable noncontrolling interest				(24.6)	(9.7)				(34.3)
Net income (loss) (excludes $2.9 million and $2.0 million attributable to redeemable noncontrolling interest in 2015 and 2014 respectively)					301.9			20.2	322.1
Other comprehensive income (loss) (excludes $(7.7) million and $1.6 million attributable to redeemable noncontrolling interest in 2015 and 2014 respectively)						178.6		(3.6)	175.0
Balances at Mar. 31, 2014	0.0	0.1	4.6	9,813.1	5,605.3	361.8	(5,797.0)	70.0	10,057.9
Balances at Dec. 31, 2014	0.0	0.1	4.6	9,945.5	6,114.1	50.4	(5,930.7)	48.0	10,232.0
Increase (decrease) in stockholders' equity
Common stock issued				17.9					17.9
Stock-based compensation and additional related tax benefits				33.2	(1.6)				31.6
Treasury stock acquired, common							(75.4)		(75.4)
Dividends to common stockholders					(106.3)				(106.3)
Dividends to preferred stockholders					(8.2)				(8.2)
Distributions to noncontrolling interest								(0.3)	(0.3)
Contributions from noncontrolling interest								1.5	1.5
Purchase of subsidiary shares from noncontrolling interest				(17.3)		(6.5)		15.1	(8.7)
Adjustments to redemption amount of redeemable noncontrolling interest				(3.7)					(3.7)
Net income (loss) (excludes $2.9 million and $2.0 million attributable to redeemable noncontrolling interest in 2015 and 2014 respectively)					422.4			3.8	426.2
Other comprehensive income (loss) (excludes $(7.7) million and $1.6 million attributable to redeemable noncontrolling interest in 2015 and 2014 respectively)						(15.9)		1.4	(14.5)
Balances at Mar. 31, 2015	$ 0.0	$ 0.1	$ 4.6	$ 9,975.6	$ 6,420.4	$ 28.0	$ (6,006.1)	$ 69.5	$ 10,492.1