Summary of Significant Accounting Policies (Details Textual) $ in Thousands	3 Months Ended				6 Months Ended
	Jun. 30, 2020 USD ($) shares	Mar. 31, 2020 shares	Jun. 30, 2019 USD ($) shares	Mar. 31, 2019 shares	Jun. 30, 2020 USD ($) shares	Jun. 30, 2019 USD ($)	Jul. 31, 2020 MMBTU $ / MMBTU	Apr. 21, 2020	Dec. 31, 2019 USD ($)
Summary of Significant Accounting Policies
Brent Spot Price		15
WTI Spot Price		21
WTI May 2020 Pricing								10
Total capitalized internal costs	$ 900		$ 1,300		$ 2,000	$ 2,900
Proved oil and gas properties	1,268,374				1,268,374				$ 1,201,296
Unproved oil and gas properties	30,043				30,043				41,201
Furniture, fixtures, and other equipment	5,134				5,134				5,220
Less - Accumulated depreciation, depletion, and amortization	(773,836)				(773,836)				(380,728)
Net Furniture, Fixtures and other equipment	529,715				529,715				866,989
Impairment of Oil and Gas Properties	260,342		0		355,948	0
Allowance for doubtful accounts receivable, current	100				100				100
Accounts receivable, gross	11,200				11,200				24,600
Accounts receivable related to joint interest owners	400				400				3,700
Severance tax receivable	6,300				6,300				5,400
Other receivables	5,600				$ 5,600				3,300
Percentage of working interest in wells					100.00%
Total amount of supervision fees charged to wells	900		1,300		$ 2,200	2,600
Income Tax Expense (Benefit)	22,420		(20,735)		21,179	(20,503)
Oil and gas sales	24,846		$ 74,703		78,222	146,768
Trade accounts payable	5,466				5,466				26,121
Accrued operating expenses	2,587				2,587				3,873
Accrued payroll costs	2,784				2,784				4,601
Asset retirement obligation - current portion	382				382				392
Accrued non-income based taxes	3,102				3,102				1,413
Accrued corporate and legal fees	158				158				109
Other payables	1,321				1,321				2,834
Accounts payable and accrued liabilities	$ 15,800				$ 15,800				$ 39,343
Purchase of treasury stock (shares) | shares	1,098	26,675	3,877	11,076	27,773
Oil sales [Member]
Summary of Significant Accounting Policies
Oil and gas sales	$ 5,265		$ 24,940		$ 23,315	39,547
Natural gas sales [Member]
Summary of Significant Accounting Policies
Oil and gas sales	18,103		43,597		49,574	94,902
NGL sales [Member]
Summary of Significant Accounting Policies
Oil and gas sales	$ 1,478		$ 6,166		$ 5,333	$ 12,319
Collar Contracts [Member] | Second Quarter 2022 | Oil Derivative Swaps [Member] | Subsequent Event [Member]
Summary of Significant Accounting Policies
Oil and Gas Production Hedged Volumes | MMBTU							86,450
Derivative, Average Floor Price | $ / MMBTU							39.00
Derivative, Average Cap Price | $ / MMBTU							46.50
Minimum [Member]
Summary of Significant Accounting Policies
Estimated useful lives of property					2 years
Maximum [Member]
Summary of Significant Accounting Policies
Estimated useful lives of property					20 years