Consolidated Statements Of Comprehensive Income (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Consolidated Statements Of Comprehensive Income [Abstract]
Net income	$ 52,988	$ 49,960	$ 159,839	$ 137,995
Unrealized loss on derivatives qualifying as hedges
Unrealized loss on cash flow hedge, net of tax	0	0	0	(10)
Less: reclassification adjustment for loss on cash flow hedge included in net income, net of tax	0	31	0	121
Unrealized gain on available for sale securities
Unrealized gain on securities, net of tax	(4)	(4)	7	3
Less: reclassification adjustment for gain on sale of securities included in net income, net of tax	(13)	(2)	(13)	(2)
Other comprehensive income	(17)	25	(6)	112
Comprehensive income	$ 52,971	$ 49,985	$ 159,833	$ 138,107