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	$ 36,648	$ 40,003	$ 121,339	$ 96,976
Other comprehensive loss:
Unrealized loss on interest rate swaps	(890)	(17,290)	(5,338)	(17,290)
Other comprehensive loss, before income taxes	(890)	(17,290)	(5,338)	(17,290)
Income tax benefit	329	6,397	1,975	6,397
Other comprehensive loss, net of income taxes	(561)	(10,893)	(3,363)	(10,893)
Comprehensive income	$ 36,087	$ 29,110	$ 117,976	$ 86,083