Consolidated Statements Of Comprehensive Income (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Consolidated Statements Of Comprehensive Income [Abstract]
Net income	$ 41,510	$ 27,155	$ 84,691	$ 56,973
Other comprehensive loss:
Unrealized loss on interest rate swaps	(3,628)		(4,448)
Other comprehensive loss, before income taxes	(3,628)		(4,448)
Income tax benefit	1,343		1,646
Other comprehensive loss, net of income taxes	(2,285)		(2,802)
Comprehensive income	$ 39,225	$ 27,155	$ 81,889	$ 56,973