Income Taxes (Components Of Income Tax Expense) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Income Taxes [Abstract]
Current income tax expense, Federal	$ 70,514	$ 62,588	$ 50,710
Current income tax expense, State	6,466	5,506	6,209
Current income tax expense, Total	76,980	68,094	56,919
Deferred income tax expense, Federal	17,167	24,035	19,803
Deferred income tax expense, State	2,154	2,168	2,819
Deferred income tax expense, Total	19,321	26,203	22,622
Income tax expense	$ 96,301	$ 94,297	$ 79,541