Income Taxes - Components of Deferred Tax Assets and Deferred Tax Liabilities (Detail) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Components of Deferred Tax Assets and Liabilities [Abstract]
Net operating loss carryforward	$ 112,898	$ 170,536
Stock-based compensation	1,962	3,826
Deferred rent	628	163
Deferred compensation	0	1,824
State tax credit carryforwards	0	6,499
Financing obligation	1,174	705
Accrued expenses	250	248
Derivative instruments	0	6,158
Other assets	2,409	228
Capital loss carryforward	1,028	0
Less: Valuation allowance	(13,215)	(114,530)
Total long-term deferred tax assets	107,134	75,657
Oil and gas properties	(219,390)	(75,409)
Long-term derivative instruments	(26,700)	0
Prepaid expenses	(374)	(248)
Deferred compensation	(204)	0
Total long-term deferred tax assets (liabilities)	(246,668)	(75,657)
Deferred Tax Liabilities, Net, Noncurrent	$ (139,534)	$ 0