Consolidated Statements of Comprehensive Income (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Net income	$ 184,746	$ 23,176	$ 195,867
Change in value of derivative instruments used as cash flow hedges, net of tax of ($4,717), $12,094, and $18,412	(7,349)	18,635	29,384
Reclassification - derivative settlements, net of tax of ($249), ($20,171), and ($1,146)	(354)	(31,682)	(1,819)
Ineffective portion of derivatives, net of tax of $74, $1,008, and ($1,061)	116	1,608	(1,688)
Total comprehensive income	$ 177,159	$ 11,737	$ 221,744