Stock Option Activity (Details) (USD $) In Millions, except Per Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Stock options outstanding as of January 1, 2011	22.2
Granted	0.8
Exercised	(1.3)	(0.5)	0
Cancelled/expired	(3.0)
Forfeited	(0.6)
Stock options outstanding as of December 31, 2011	18.1	22.2
Stock options outstanding as of Jan 1, 2011, Weighted-average exercise price	$ 14.43
Granted, Weighted-average exercise price	$ 12.48
Exercised, Weighted-average exercise price	$ 9.61
Cancelled/expired, Weighted-average exercise price	$ 31.19
Forfeited, Weighted-average exercise price	$ 5.73
Stock options outstanding as of Dec 31, 2011, Weighted-average exercise price	$ 12.10	$ 14.43
Stock options outstanding, Weighted-average remaining contractual term	4.4
Stock options outstanding, Aggregate intrinsic value	$ 20.7
Stock options vested and expected to vest, Outstanding	17.2
Stock options vested and expected to vest, Weighted-average exercise price	$ 12.37
Stock options vested and expected to vest, Weighted-average remaining contractual term	4.3
Stock options vested and expected to vest, Aggregate intrinsic value	17.8
Stock options exercisable, Number	13.1
Stock options exercisable, Weighted-average exercise price	$ 14.16
Stock options exercisable, Weighted-average remaining contractual term	3.2
Stock options exercisable, Aggregate intrinsic value	3.3
Non-vested as of January 1, 2011	6.5
Granted	0.8
Vested	(1.7)
Forfeited	(0.6)
Non-vested as of December 31, 2011	5.0	6.5
Non-vested as of January 1, 2011, Weighted-average grant date fair value	$ 3.38
Granted, Weighted-average grant date fair value	$ 4.57	$ 3.88	$ 2.69
Vested, Weighted-average grant date fair value	$ 4.27
Forfeited, Weighted-average grant date fair value	$ 3.11
Non-vested as of December 31, 2011, Weighted-average grant date fair value	$ 3.31	$ 3.38
Non-vested options outstanding, Weighted-average remaining contractual term	7.5
Non-vested options outstanding, Aggregate intrinsic value	17.5
Intrinsic value of stock options exercised	3.2	0.6	0
Cash received from stock options exercised	$ 13.3	$ 4.8	$ 0