Income Taxes (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Federal:
Current	$ 45,765	$ 51,717	$ 49,416
Deferred	17,330	11,536	20,910
Federal, Total	63,095	63,253	70,326
State:
Current	10,710	12,892	10,564
Deferred	2,222	1,957	3,690
State, Total	12,932	14,849	14,254
Income Tax Expense (Benefit), Total	$ 76,027	$ 78,102	$ 84,580