Stock-Based Compensation (Details 3) (USD $) In Millions, except Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Weighted Average Grant-Date Fair Value
Increase or decrease in tax benefits from restricted stock units and exercise of nonqualified stock options	$ 1.1	$ (0.1)	$ (0.3)
Stock options
Shares Under Option
Granted (in shares)	617,500
Forfeited (in shares)	(28,500)
Outstanding at the end of the period (in shares)	589,000
Weighted Average Grant-Date Fair Value
Granted (in dollars per share)	$ 10.90
Cancelled (in dollars per share)	$ 10.90
Outstanding at the end of the period (in dollars per share)	$ 10.90