Summary of Significant Accounting Policies (Details Textual) $ in Thousands		3 Months Ended						9 Months Ended
	Dec. 15, 2017	Sep. 30, 2020 USD ($) MMBTU $ / MMBTU shares	Jun. 30, 2020 shares	Mar. 31, 2020 shares	Sep. 30, 2019 USD ($) shares	Jun. 30, 2019 shares	Mar. 31, 2019 shares	Sep. 30, 2020 USD ($) MMBTU $ / MMBTU shares	Sep. 30, 2019 USD ($)	Nov. 02, 2020 USD ($)	Oct. 31, 2020 MMBTU $ / MMBTU	May 12, 2020 USD ($)	Apr. 21, 2020	Dec. 31, 2019 USD ($)
Summary of Significant Accounting Policies
Brent Spot Price		42	41	15				42
WTI Spot Price		40	39	21				40
WTI May 2020 Pricing													10
Total capitalized internal costs		$ 800			$ 1,200			$ 2,800	$ 4,100
Proved oil and gas properties		1,287,962						1,287,962						$ 1,201,296
Unproved oil and gas properties		30,661						30,661						41,201
Furniture, fixtures, and other equipment		5,166						5,166						5,220
Less - Accumulated depreciation, depletion, and amortization		(787,830)						(787,830)						(380,728)
Net Furniture, Fixtures and other equipment		535,959						535,959						866,989
Impairment of Oil and Gas Properties		0			0			355,948	0
Allowance for doubtful accounts receivable, current		100						100						100
Accounts receivable, gross		17,800						17,800						24,600
Accounts receivable related to joint interest owners		500						500						3,700
Severance tax receivable		6,400						6,400						5,400
Other receivables		4,200						$ 4,200						3,300
Percentage of working interest in wells								100.00%
Total amount of supervision fees charged to wells		$ 1,100			1,100			$ 3,200	3,700
Effective Income Tax Rate Reconciliation, Percent		7.70%						(6.90%)
Provision (Benefit) for Income Taxes		$ (572)			1,039			$ 20,607	(19,464)
Oil and gas sales		45,699			$ 72,014			123,921	218,781
Trade accounts payable		8,063						8,063						26,121
Accrued operating expenses		2,816						2,816						3,873
Accrued payroll costs		3,414						3,414						4,601
Asset retirement obligation - current portion		439						439						392
Accrued non-income based taxes		4,133						4,133						1,413
Accrued corporate and legal fees		162						162						109
Other payables		3,680						3,680						2,834
Accounts payable and accrued liabilities		$ 22,707						$ 22,707						$ 39,343
Purchase of treasury stock (shares) | shares		958	1,098	26,675	411	3,877	11,076	28,731
New Credit Facility [Member] | Line of Credit [Member]
Summary of Significant Accounting Policies
Line of Credit Facility, Current Borrowing Capacity												$ 330,000
Second Lien Notes [Member]
Summary of Significant Accounting Policies
Discount rate for estimated future net revenues from proved properties	10.00%
Oil sales [Member]
Summary of Significant Accounting Policies
Oil and gas sales		$ 17,665			$ 28,894			$ 40,979	68,441
Natural gas sales [Member]
Summary of Significant Accounting Policies
Oil and gas sales		23,595			37,040			73,170	131,941
NGL sales [Member]
Summary of Significant Accounting Policies
Oil and gas sales		$ 4,439			$ 6,080			$ 9,772	$ 18,400
Subsequent Event [Member] | New Credit Facility [Member] | Line of Credit [Member]
Summary of Significant Accounting Policies
Line of Credit Facility, Current Borrowing Capacity										$ 310,000
Collar Contracts [Member] | First Quarter 2021 [Member] | Oil Derivative Swaps [Member]
Summary of Significant Accounting Policies
Oil and Gas Production Hedged Volumes | MMBTU		155,475						155,475
Derivative, Average Floor Price | $ / MMBTU		34.15						34.15
Derivative, Average Cap Price | $ / MMBTU		39.24						39.24
Collar Contracts [Member] | First Quarter 2021 [Member] | Natural Gas Derivative Swaps [Member]
Summary of Significant Accounting Policies
Oil and Gas Production Hedged Volumes | MMBTU		7,027,800						7,027,800
Derivative, Average Floor Price | $ / MMBTU		2.53						2.53
Derivative, Average Cap Price | $ / MMBTU		3.33						3.33
Collar Contracts [Member] | First Quarter 2022 | Oil Derivative Swaps [Member] | Subsequent Event [Member]
Summary of Significant Accounting Policies
Oil and Gas Production Hedged Volumes | MMBTU											40,500
Derivative, Average Floor Price | $ / MMBTU											40.00
Derivative, Average Cap Price | $ / MMBTU											45.55
Collar Contracts [Member] | First Quarter 2022 | Natural Gas Derivative Swaps [Member]
Summary of Significant Accounting Policies
Oil and Gas Production Hedged Volumes | MMBTU		4,415,000						4,415,000
Derivative, Average Floor Price | $ / MMBTU		2.50						2.50
Derivative, Average Cap Price | $ / MMBTU		3.35						3.35
Collar Contracts [Member] | Second Quarter 2022 | Oil Derivative Swaps [Member]
Summary of Significant Accounting Policies
Oil and Gas Production Hedged Volumes | MMBTU		86,450						86,450
Derivative, Average Floor Price | $ / MMBTU		39.00						39.00
Derivative, Average Cap Price | $ / MMBTU		46.50						46.50
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											29,400
Derivative, Average Floor Price | $ / MMBTU											40.00
Derivative, Average Cap Price | $ / MMBTU											45.30
Collar Contracts [Member] | Second Quarter 2022 | Natural Gas Derivative Swaps [Member]
Summary of Significant Accounting Policies
Oil and Gas Production Hedged Volumes | MMBTU		4,200,000						4,200,000
Derivative, Average Floor Price | $ / MMBTU		2.23						2.23
Derivative, Average Cap Price | $ / MMBTU		2.70						2.70
Collar Contracts [Member] | Third Quarter 2022 | Natural Gas Derivative Swaps [Member] | Subsequent Event [Member]
Summary of Significant Accounting Policies
Oil and Gas Production Hedged Volumes | MMBTU											920,000
Derivative, Average Floor Price | $ / MMBTU											2.35
Derivative, Average Cap Price | $ / MMBTU											2.65
Basis Swap [Member] | First Quarter 2021 [Member] | Natural Gas Basis Derivative Swaps [Member]
Summary of Significant Accounting Policies
Oil and Gas Production Hedged Volumes | MMBTU		9,900,000						9,900,000
Derivative, Swap Type, Fixed Price | $ / MMBTU		(0.02)						(0.02)
Basis Swap [Member] | First Quarter 2022 | Natural Gas Basis Derivative Swaps [Member] | Subsequent Event [Member]
Summary of Significant Accounting Policies
Oil and Gas Production Hedged Volumes | MMBTU											1,800,000
Derivative, Swap Type, Fixed Price | $ / MMBTU											(0.08)
Basis Swap [Member] | Second Quarter 2022 | Natural Gas Basis Derivative Swaps [Member] | Subsequent Event [Member]
Summary of Significant Accounting Policies
Oil and Gas Production Hedged Volumes | MMBTU											1,820,000
Derivative, Swap Type, Fixed Price | $ / MMBTU											(0.08)
Basis Swap [Member] | Third Quarter 2022 | Natural Gas Basis Derivative Swaps [Member] | Subsequent Event [Member]
Summary of Significant Accounting Policies
Oil and Gas Production Hedged Volumes | MMBTU											1,840,000
Derivative, Swap Type, Fixed Price | $ / MMBTU											(0.08)
Basis Swap [Member] | Fourth Quarter 2022 | Natural Gas Basis Derivative Swaps [Member] | Subsequent Event [Member]
Summary of Significant Accounting Policies
Oil and Gas Production Hedged Volumes | MMBTU											1,840,000
Derivative, Swap Type, Fixed Price | $ / MMBTU											(0.08)
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