Summary of Significant Accounting Policies (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017	Mar. 31, 2017	Dec. 31, 2016
Property and Equipment
Proved oil and gas properties	$ 664,742	$ 658,519
Unproved oil and gas properties	55,725	50,377
Furniture, fixtures, and other equipment	3,361	3,270
Less - Accumulated depreciation, depletion, and amortization	(229,901)	(216,769)
Net Furniture, Fixtures and other equipment	493,927	495,397
Accounts Payable and Accrued Liabilities
Trade accounts payable	15,440	20,884
Accrued operating expenses	2,964	3,490
Accrued compensation costs	1,956	5,334
Asset retirement obligation - current portion	467	2,109
Accrued non-income based taxes	4,058	3,898
Accrued corporate and legal fees	2,982	2,784
Other payables	4,422	5,938
Total accounts payable and accrued liabilities	32,289	44,437
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents [Abstract]
Cash and cash equivalents	237	7,806	$ 168
Long-term restricted cash	220	220	832
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents	$ 457	$ 8,026	$ 1,000	$ 497