Accumulated Other Comprehensive Income (Loss) - Schedule of Changes in Accumulated Other Comprehensive Income Loss (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance, net of tax	$ 83,315	$ (2,062)	$ 28,833
Other comprehensive income (loss) before reclassifications:
Change in fair value of derivatives	52,630	136,097	(26,945)
Foreign currency translations	(2,605)	(2,801)	(667)
Income tax effect	(19,096)	(48,995)	9,701
Net of tax	30,929	84,301	(17,911)
Amounts reclassified from accumulated other comprehensive income:
Ending balance, net of tax	17,952	83,315	(2,062)
Reclassification out of Accumulated Other Comprehensive Income [Member]
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance, net of tax	83,315	(2,062)
Amounts reclassified from accumulated other comprehensive income:
Operating revenue: oil/natural gas production	149,955	526	20,289
Derivative income, net	1,170	(2,208)
Income tax effect	(54,833)	606	(7,305)
Net of tax	96,292	(1,076)	12,984
Other comprehensive loss, net of tax	(65,363)	85,377	(30,895)
Ending balance, net of tax	17,952	83,315	(2,062)
Cash Flow Hedges [Member]
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance, net of tax	86,783	(1,395)	28,833
Other comprehensive income (loss) before reclassifications:
Change in fair value of derivatives	52,630	136,097	(26,945)
Foreign currency translations	0	0	0
Income tax effect	(19,096)	(48,995)	9,701
Net of tax	33,534	87,102	(17,244)
Amounts reclassified from accumulated other comprehensive income:
Ending balance, net of tax	24,025	86,783	(1,395)
Cash Flow Hedges [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member]
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance, net of tax	86,783	(1,395)
Amounts reclassified from accumulated other comprehensive income:
Operating revenue: oil/natural gas production	149,955	526	20,289
Derivative income, net	1,170	(2,208)
Income tax effect	(54,833)	606	(7,305)
Net of tax	96,292	(1,076)	12,984
Other comprehensive loss, net of tax	(62,758)	88,178	(30,228)
Ending balance, net of tax	24,025	86,783	(1,395)
Foreign Currency Items [Member]
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance, net of tax	(3,468)	(667)	0
Other comprehensive income (loss) before reclassifications:
Change in fair value of derivatives	0	0	0
Foreign currency translations	(2,605)	(2,801)	(667)
Income tax effect	0	0	0
Net of tax	(2,605)	(2,801)	(667)
Amounts reclassified from accumulated other comprehensive income:
Ending balance, net of tax		(3,468)	(667)
Foreign Currency Items [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member]
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance, net of tax	(3,468)	(667)
Amounts reclassified from accumulated other comprehensive income:
Operating revenue: oil/natural gas production	0	0	0
Derivative income, net	0	0
Income tax effect	0	0	0
Net of tax	0	0	0
Other comprehensive loss, net of tax	(2,605)	(2,801)	(667)
Ending balance, net of tax	$ (6,073)	$ (3,468)	$ (667)