Supplemental Oil and Natural Gas Information - Changes in Standardized Measure of Discounted Net Cash Flows (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Increase (Decrease) in Standardized Measure of Discounted Future Net Cash Flow Relating to Proved Oil and Gas Reserves [Roll Forward]
Standardized Measure, beginning of the year	$ 212,865	$ 330,657	$ 155,295
Net change in prices and production costs	(33,507)	(372,664)	(52,642)
Net change in future development costs	1,552	79,244	(2,122)
Sales, less production costs	(99,768)	(121,646)	(104,099)
Extensions	79,941	107,749	491,067
Acquisitions	1,045
Divestitures	(5,231)
Revisions of previous quantity estimates	15,754	(97,210)	(38,201)
Previously estimated development costs incurred	4,886	62,906	16,807
Accretion of discount	21,287	50,939	15,529
Net change in taxes		178,732	(178,732)
Changes in timing and other	7,157	(5,842)	27,755
Standardized Measure, end of year	$ 205,981	$ 212,865	$ 330,657