Supplemental Oil and Gas Disclosures - Results of Operations for Oil and Natural Gas Producing Activities (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Oil and Gas Exploration and Production Industries Disclosures [Abstract]
Revenues	$ 721,672	$ 1,304,004	$ 1,084,412
Production costs	245,675	326,381	221,095
Depreciation, depletion and amortization	472,800	400,118	298,999
Exploration costs	2,369	3,064	2,260
Rig termination	3,895	0	0
Impairment of oil and gas properties	46,109	47,238	1,168
Income tax expense (benefit)	(18,382)	197,701	196,312
Results of operations for oil and natural gas producing activities	$ (30,794)	$ 329,502	$ 364,578