Supplemental Oil and Natural Gas Information - Standardized Measure of Discounted Net Future Cash Flows (Detail) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Future Net Cash Flows Relating to Proved Oil and Gas Reserves, Net Cash Flows [Abstract]
Future cash inflows (total revenues)	$ 1,143,142	$ 975,664	$ 1,870,319
Future production costs	(725,724)	(592,073)	(728,041)
Future development costs (capital costs)	(116,988)	(83,532)	(350,187)
Future income tax expense			(277,500)
Future net cash flows	300,430	300,059	514,591
10% annual discount for estimated timing of cash flows	(94,449)	(87,194)	(183,934)
Standardized measure of Discounted Future Net Cash Flow	$ 205,981	$ 212,865	$ 330,657	$ 155,295