Stock Repurchases (Details) (USD $)	12 Months Ended			60 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2010
Stock Repurchases [Abstract]
Stock Repurchase Program, Remaining Authorized Repurchase Amount	$ 100,000,000
Stock Repurchased During Period, Shares	983,818	3,510,973		961,335
Payments for Repurchase of Common Stock	(18,374,000)	(63,659,000)	(10,650,000)	12,600,000
Stock Repurchase Program, Remaining Authorized Repurchase Amount	$ 5,400,000