Income Taxes (Schedule Of Components Of Income Tax Expense (Benefit)) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Income Taxes [Abstract]
Current, Federal									$ 44,268	$ 29,932	$ (1,714)
Deferred, Federal									(426)	(40)	6,364
Total, Federal									43,842	29,892	4,650
Current, State									2,632	4,810	3,126
Deferred, State									6,847	2,040	(1,971)
Total, State									9,479	6,850	1,155
Current Income Tax Expense (Benefit)									46,900	34,742	1,412
Deferred Income Tax Expense (Benefit)									6,421	2,000	4,393
Total	$ 14,796	$ 13,587	$ 11,681	$ 13,257	$ 10,722	$ 10,717	$ 8,782	$ 6,521	$ 53,321	$ 36,742	$ 5,805