Consolidated Statements Of Comprehensive Income (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Statement of Comprehensive Income [Abstract]
Net income	$ (20,956)	$ 31,296	$ 94,960	$ 72,649	$ 15,376	$ 39,570	$ (9,264)	$ 66,461	$ 177,949	$ 112,143	$ 116,911
Other comprehensive income, before tax:
Gains on hedging instrument									0	0	0
Other comprehensive income, before tax									0	0	0
Income tax expense related to gains on hedging instrument									0	0	0
Other comprehensive income, net of tax:									0	0	0
Comprehensive income									$ 177,949	$ 112,143	$ 116,911