Condensed Consolidated Statements Of Comprehensive Income (USD $) In Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2011	Jun. 30, 2010	Jun. 30, 2011	Jun. 30, 2010
Condensed Consolidated Statements Of Comprehensive Income
Net income	$ 49,819	$ 32,175	$ 90,846	$ 68,328
Other comprehensive income (loss), net of taxes:
Change in value of derivative instruments used as cash flow hedges, net of tax of $10,371, $1,360, $1,187 and $16,027	16,796	2,194	1,968	25,866
Reclassification - derivative settlements, net of tax of $1,906, ($6,048), $1,779 and ($8,062)	3,045	(9,764)	2,840	(13,016)
Ineffective portion of derivatives, net of tax of $(1,432), $253, ($702) and ($164)	(2,299)	409	(1,120)	(265)
Comprehensive income	$ 67,361	$ 25,014	$ 94,534	$ 80,913