Income Taxes - Components of Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Deferred noncurrent income tax assets (liabilities):
Office and other equipment	$ (48)	$ (253)
Oil & gas properties	7,428	23,177
Asset retirement obligation	2,042	1,788
Basis difference in subsidiary obligation	(4,226)
Intangible assets (liabilities)	36	(7)
Unrealized derivative loss (gain)	2,145	(1,284)
Stock-based compensation	1,148
Federal net operating loss carryforward	15,109	339
Other	186	59
Net deferred noncurrent tax assets	23,820	23,819
Valuation allowance	(39,596)	$ (23,819)
Net deferred tax (liability) asset	$ (15,776)