CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (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 Income And Comprehensive Income [Abstract]
Net income	$ 146,418		$ 19,178		$ 350,328		$ 87,551
Other comprehensive income:
Realized gain on hedge derivative contract settlements reclassified into natural gas, NGLs and oil sales from other comprehensive income, net of taxes							(14,840)	[1]
De-designated hedges reclassified into natural gas, NGLs and oil sales, net of taxes	(2,172)	[2]	(16,717)	[2]	(6,458)	[2]	(42,758)	[2]
De-designated hedges reclassified to derivative fair value income, net of taxes			(438)	[3]			(2,376)	[3]
Change in unrealized deferred hedging gains, net of taxes							(4,203)	[4]
Total comprehensive income	$ 144,246		$ 2,023		$ 343,870		$ 23,374

[1] Amount is net of income tax benefit of $9,488 for the nine months ended September 30, 2013.

[2] Amounts are net of income tax benefit of $1,332 for the three months ended September 30, 2014 and $4,122 for the nine months ended September 30, 2014. Amounts are net of income tax benefit of $10,688 for the three months ended September 30, 2013 and $27,337 for the nine months ended September 30, 2013.

[3] Amounts relate to transactions not probable of occurring and are presented net of income tax benefit of $279 for the three months ended September 30, 2013 and $1,518 for the nine months ended September 30, 2013.

[4] Amount is net of income tax benefit of $2,687 for the nine months ended September 30, 2013.