Treasury Stock (Details) (USD $) Share data in Millions, except Per Share data, unless otherwise specified	1 Months Ended		4 Months Ended	12 Months Ended
	Feb. 29, 2012	Aug. 30, 2011	Dec. 31, 2011	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Equity, Class of Treasury Stock [Line Items]
Stock Repurchase Program, Authorized Amount	$ 150,000,000	$ 150,000,000
Treasury Stock, Shares, Acquired			28.6
Treasury Stock, Value, Acquired, Cost Method, Net of Commissions			128,900,000
Share Repurchase Program Commission Incurred			600,000
Treasury Stock Acquired, Average Cost Per Share			$ 4.51
Stock Repurchase Program, Remaining Authorized Repurchase Amount			21,100,000
Other Accrued Liabilities, Current			1,100,000	1,100,000
Adjustments Related to Tax Withholding for Share-based Compensation				776,000	284,000
Payments Related to Tax Withholding for Share-based Compensation				$ 776,000	$ 0	$ 0