Treasury Stock (Details) (USD $) Share data in Millions, except Per Share data, unless otherwise specified	3 Months Ended	6 Months Ended		23 Months Ended
	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013
Equity, Class of Treasury Stock [Line Items]
Treasury Stock, Value, Acquired, Cost Method		$ 172,000	$ 446,000
Stock Repurchase Program [Member]
Equity, Class of Treasury Stock [Line Items]
Stock Repurchase Program, Authorized Amount				300,000,000
Treasury stock, shares, acquired (in shares)	7.1	0	8.1	45.0
Treasury Stock, Value, Acquired, Cost Method	33,200,000		37,700,000	208,400,000
Share Repurchase Program Commission Incurred	100,000		200,000	900,000
Treasury Stock Acquired, Average Cost Per Share	$ 4.66		$ 4.65
Accrued Liability for Repurchased but Unpaid Treasury Stock		0		0
Stock Repurchase Program, Remaining Authorized Repurchase Amount		$ 91,600,000