Income Tax - Components of Deferred Tax Assets and Liabilities (Detail) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Deferred tax asset:
Oil and gas properties and equipment	$ 62,616	$ 93,854	$ 193,095
Federal tax loss carryforwards	140,059	114,652	145,628
Derivative instruments and other		1,064	16,829
Other, net	7,398	4,639	4,259
Deferred tax asset	210,073	214,209	359,811
Valuation allowance	(208,324)	(213,800)	(359,098)
Net deferred tax assets	1,749	409	713
Deferred tax liability:
Derivative instruments and other	1,197
Other, net	552	409	713
Net deferred tax liability	$ 1,749	$ 409	$ 713