Share-Based Compensation (Details 3) (USD $) In Millions, except Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Weighted-Average Grant-Date Fair Value
Granted (in dollars per share)	$ 9.40	$ 6.24	$ 6.62
Unvested Stock Options
Unvested stock options
Options outstanding at the beginning of the period (in shares)	2,900,000
Granted (in shares)	658,000
Vested (in shares)	(1,773,000)
Forfeited (in shares)	(159,000)
Options outstanding at the end of the period (in shares)	1,626,000
Weighted-Average Grant-Date Fair Value
Options outstanding at the end of the period (in dollars per share)	$ 3.88
Granted (in dollars per share)	$ 9.40
Vested (in dollars per share)	$ 4.44
Forfeited (in dollars per share)	$ 2.81
Options outstanding at the beginning of the period (in dollars per share)	$ 5.62
Total future compensation cost related to unvested options that are expected to vest	$ 5.9
Maximum Weighted Average Period for Cost recognition	2 years
Stock options
Unvested stock options
Options outstanding at the beginning of the period (in shares)	27,870,000
Granted (in shares)	658,000	930,753	32,115
Forfeited (in shares)	(350,000)
Options outstanding at the end of the period (in shares)	22,464,000	27,870,000
Weighted-Average Grant-Date Fair Value
Total intrinsic value of stock options exercised	23.7	18.3	6.9
Total fair value of option vested during the period	$ 7.9	$ 5.2	$ 5.6