Income Taxes (Schedule Of Components Of Provision For Income Taxes) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Income Taxes [Abstract]
Current tax, U.S. Federal	$ 100,983	$ 83,850	$ 56,945
Current tax, U.S. State	21,848	15,745	12,151
Current tax, Foreign	(6)	6	(139)
Current tax, Total	122,825	99,601	68,957
Deferred tax, U.S. Federal	12,080	10,058	9,677
Deferred tax, U.S. State	(50)	6	(1,393)
Deferred tax, Foreign	(711)		(2)
Deferred tax, Total	11,319	10,064	8,282
Valuation allowance	616	415	141
Total provision for income taxes	$ 134,760	$ 110,080	$ 77,380