Condensed Consolidated Statements Of Comprehensive Income (USD $) In Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2011	Sep. 30, 2010
Condensed Consolidated Statements Of Comprehensive Income
Net income	$ 53,360	$ 34,491	$ 144,206	$ 102,819
Other comprehensive income (loss), net of taxes:
Change in value of derivative instruments used as cash flow hedges, net of tax of $27,015, $2,753, $28,201 and $18,780	43,154	4,148	45,123	30,014
Reclassification - derivative settlements, net of tax of ($771), ($5,646), $1,008 and ($13,708)	(1,232)	(8,816)	1,608	(21,832)
Ineffective portion of derivatives, net of tax of ($899), ($67), ($1,601) and ($231)	(1,437)	(109)	(2,557)	(374)
Comprehensive income	$ 93,845	$ 29,714	$ 188,380	$ 110,627