Income Taxes (Details 3) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Income Tax Expense Reconciliation
Income taxes computed at the Federal statutory rate	$ 72,652	$ 112,838	$ 104,445
State income taxes, net of Federal income tax benefit	8,071	7,731	7,467
Other, net	(2,567)	(4,181)	(5,678)
Total	$ 78,156	$ 116,388	$ 106,234