Summary of Significant Accounting Policies (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018	Dec. 31, 2018
Property and Equipment
Proved oil and gas properties	$ 1,090,496		$ 1,090,496		$ 925,865
Unproved oil and gas properties	49,866		49,866		56,715
Furniture, fixtures, and other equipment	3,855		3,855		3,520
Less - Accumulated depreciation, depletion, and amortization	(330,638)		(330,638)		(284,804)
Net Furniture, Fixtures and other equipment	813,579		813,579		701,296
Disaggregation of Revenue [Line Items]
Oil and gas sales	74,703	$ 51,347	146,768	$ 104,099
Accounts Payable and Accrued Liabilities
Trade accounts payable	18,560		18,560		32,683
Accrued operating expenses	3,410		3,410		3,549
Accrued compensation costs	3,175		3,175		4,785
Asset retirement obligation - current portion	270		270		302
Accrued non-income based taxes	4,279		4,279		3,583
Accrued corporate and legal fees	239		239		534
Other payables	3,387		3,387		3,485
Total accounts payable and accrued liabilities	33,320		33,320		$ 48,921
Oil sales [Member]
Disaggregation of Revenue [Line Items]
Oil and gas sales	24,940	9,638	39,547	21,078
Natural gas sales [Member]
Disaggregation of Revenue [Line Items]
Oil and gas sales	43,587	36,369	94,874	72,136
NGL sales [Member]
Disaggregation of Revenue [Line Items]
Oil and gas sales	6,166	5,339	12,319	10,900
Other sales [Member]
Disaggregation of Revenue [Line Items]
Oil and gas sales	$ 10	$ 0	$ 28	$ (14)