Consolidated Statements of Comprehensive Income (Unaudited) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Statement of Comprehensive Income [Abstract]
Net income (loss)	$ 19,151	$ (74,558)	$ 28,064	$ (18,640)
Other comprehensive income, net of tax:
Net change in fair value of derivatives, net of tax expense of $78 and $21 for the three months ended and $389 and $825 for the nine months ended September 30, 2013 and 2014, respectively	1,643	1,798	2,025	13,751
Net derivative loss reclassified into earnings	8,549	7,300	26,730	25,285
Other comprehensive income	10,192	9,098	28,755	39,036
Total comprehensive income (loss)	$ 29,343	$ (65,460)	$ 56,819	$ 20,396