Summary of Significant Accounting Policies (Details Textual) $ in Thousands, MMcf in Millions	6 Months Ended	12 Months Ended
	Jun. 30, 2020 USD ($)	Dec. 31, 2020 USD ($) bbl MMBTU $ / MMBTU $ / Boe shares	Dec. 31, 2019 USD ($) shares	Feb. 26, 2021 MMBTU bbl $ / MMBTU $ / Boe	Sep. 30, 2020 MMcf	Apr. 21, 2020	Mar. 31, 2020
Summary of Significant Accounting Policies (Textual) [Abstract]
Brent Spot Price	41	52			42		15
WTI Spot Price	39	49			40		21
WTI May 2020 Pricing						10
Curtailed Natural Gas Volumes | MMcf					20
Total capitalized internal costs | $		$ 3,500	$ 5,300
Write-down of oil and gas properties | $		$ 355,948	0
Discount rate for estimated future net revenues from proved properties		10.00%
Revenue from Contract with Customer, Excluding Assessed Tax | $		$ 177,386	288,631
Allowance for doubtful accounts receivable, current | $		100	100
Accounts receivable from oil and gas sales | $		18,800	24,600
Accounts receivable related to joint interest owners | $		4,000	3,700
Severance tax credit receivables | $		2,400	5,400
Other receivables | $		$ 700	3,300
Percentage of working interest in wells		100.00%
Total amount of supervision fees charged to wells | $		$ 4,400	4,900
Income Tax Expense (Benefit) | $	$ 21,200	20,911	(21,582)
Current State and Local Tax Expense (Benefit) | $		$ (1,800)	$ 1,100
Treasury Stock, Shares, Acquired | shares		28,731	22,482
Operating Lease, Right-of-Use Asset | $		$ 4,366	$ 9,374
Concentration Risk, Percentage		10.00%
First Quarter 2021 [Member] | Natural Gas Basis Derivative [Member] | Basis Swap [Member]
Summary of Significant Accounting Policies (Textual) [Abstract]
Derivative, Swap Type, Average Fixed Price		(0.022)
First Quarter 2021 [Member] | Natural Gas Derivative [Member] | Collar Contracts [Member]
Summary of Significant Accounting Policies (Textual) [Abstract]
Derivative, Nonmonetary Notional Amount | MMBTU		7,027,800
Derivative, Average Floor Price		2.53
Derivative, Average Cap Price		3.33
First Quarter 2021 [Member] | Natural Gas Derivative [Member] | Swap [Member]
Summary of Significant Accounting Policies (Textual) [Abstract]
Derivative, Swap Type, Average Fixed Price		2.74
First Quarter 2021 [Member] | Oil Derivative [Member] | Collar Contracts [Member]
Summary of Significant Accounting Policies (Textual) [Abstract]
Derivative, Nonmonetary Notional Amount | MMBTU		155,475
Derivative, Average Floor Price		34.15
Derivative, Average Cap Price		39.24
First Quarter 2021 [Member] | Oil Derivative [Member] | Swap [Member]
Summary of Significant Accounting Policies (Textual) [Abstract]
Derivative, Swap Type, Average Fixed Price | $ / Boe		51.89
First Quarter 2021 [Member] | Oil Basis Calendar Monthly Roll Differential Swap | Basis Swap [Member]
Summary of Significant Accounting Policies (Textual) [Abstract]
Derivative, Nonmonetary Notional Amount | bbl		367,000
Derivative, Swap Type, Average Fixed Price		(0.40)
First Quarter 2021 [Member] | Swap Purchase | Swap [Member] | Subsequent Event
Summary of Significant Accounting Policies (Textual) [Abstract]
Derivative, Nonmonetary Notional Amount | bbl				13,750
Derivative, Swap Type, Average Fixed Price | $ / Boe				53.10
First Quarter 2021 [Member] | NGL Contract | Swap [Member] | Subsequent Event
Summary of Significant Accounting Policies (Textual) [Abstract]
Derivative, Nonmonetary Notional Amount | bbl				101,714
Derivative, Swap Type, Average Fixed Price | $ / Boe				23.14
Second Quarter 2021 [Member] | Natural Gas Basis Derivative [Member] | Basis Swap [Member]
Summary of Significant Accounting Policies (Textual) [Abstract]
Derivative, Swap Type, Average Fixed Price		(0.022)
Second Quarter 2021 [Member] | Natural Gas Derivative [Member] | Collar Contracts [Member]
Summary of Significant Accounting Policies (Textual) [Abstract]
Derivative, Nonmonetary Notional Amount | MMBTU		5,911,000
Derivative, Average Floor Price		2.26
Derivative, Average Cap Price		2.70
Second Quarter 2021 [Member] | Natural Gas Derivative [Member] | Collar Contracts [Member] | Subsequent Event
Summary of Significant Accounting Policies (Textual) [Abstract]
Derivative, Nonmonetary Notional Amount | MMBTU				1,820,000
Derivative, Average Floor Price				2.83
Derivative, Average Cap Price				2.98
Second Quarter 2021 [Member] | Natural Gas Derivative [Member] | Swap [Member]
Summary of Significant Accounting Policies (Textual) [Abstract]
Derivative, Swap Type, Average Fixed Price		2.42
Second Quarter 2021 [Member] | Oil Derivative [Member] | Collar Contracts [Member]
Summary of Significant Accounting Policies (Textual) [Abstract]
Derivative, Nonmonetary Notional Amount | MMBTU		116,980
Derivative, Average Floor Price		34.33
Derivative, Average Cap Price		40.30
Second Quarter 2021 [Member] | Oil Derivative [Member] | Swap [Member]
Summary of Significant Accounting Policies (Textual) [Abstract]
Derivative, Swap Type, Average Fixed Price | $ / Boe		51.93
Second Quarter 2021 [Member] | Oil Basis Calendar Monthly Roll Differential Swap | Basis Swap [Member]
Summary of Significant Accounting Policies (Textual) [Abstract]
Derivative, Nonmonetary Notional Amount | bbl		313,900
Derivative, Swap Type, Average Fixed Price		(0.37)
Second Quarter 2021 [Member] | Swap Purchase | Swap [Member] | Subsequent Event
Summary of Significant Accounting Policies (Textual) [Abstract]
Derivative, Nonmonetary Notional Amount | bbl				51,050
Derivative, Swap Type, Average Fixed Price | $ / Boe				53.22
Second Quarter 2021 [Member] | NGL Contract | Swap [Member] | Subsequent Event
Summary of Significant Accounting Policies (Textual) [Abstract]
Derivative, Nonmonetary Notional Amount | bbl				144,733
Derivative, Swap Type, Average Fixed Price | $ / Boe				24.13
Third Quarter 2021 [Member] | Natural Gas Basis Derivative [Member] | Basis Swap [Member]
Summary of Significant Accounting Policies (Textual) [Abstract]
Derivative, Swap Type, Average Fixed Price		(0.022)
Third Quarter 2021 [Member] | Natural Gas Derivative [Member] | Collar Contracts [Member]
Summary of Significant Accounting Policies (Textual) [Abstract]
Derivative, Nonmonetary Notional Amount | MMBTU		6,045,175
Derivative, Average Floor Price		2.15
Derivative, Average Cap Price		2.70
Third Quarter 2021 [Member] | Natural Gas Derivative [Member] | Collar Contracts [Member] | Subsequent Event
Summary of Significant Accounting Policies (Textual) [Abstract]
Derivative, Nonmonetary Notional Amount | MMBTU				1,850,000
Derivative, Average Floor Price				2.88
Derivative, Average Cap Price				3.09
Third Quarter 2021 [Member] | Natural Gas Derivative [Member] | Swap [Member]
Summary of Significant Accounting Policies (Textual) [Abstract]
Derivative, Swap Type, Average Fixed Price		2.62
Third Quarter 2021 [Member] | Oil Derivative [Member] | Collar Contracts [Member]
Summary of Significant Accounting Policies (Textual) [Abstract]
Derivative, Nonmonetary Notional Amount | MMBTU		90,620
Derivative, Average Floor Price		34.34
Derivative, Average Cap Price		39.87
Third Quarter 2021 [Member] | Oil Derivative [Member] | Swap [Member]
Summary of Significant Accounting Policies (Textual) [Abstract]
Derivative, Swap Type, Average Fixed Price | $ / Boe		51.19
Third Quarter 2021 [Member] | Oil Basis Calendar Monthly Roll Differential Swap | Basis Swap [Member]
Summary of Significant Accounting Policies (Textual) [Abstract]
Derivative, Nonmonetary Notional Amount | bbl		253,000
Derivative, Swap Type, Average Fixed Price		(0.34)
Third Quarter 2021 [Member] | NGL Contract | Swap [Member] | Subsequent Event
Summary of Significant Accounting Policies (Textual) [Abstract]
Derivative, Nonmonetary Notional Amount | bbl				146,324
Derivative, Swap Type, Average Fixed Price | $ / Boe				24.13
Fourth Quarter 2021 [Member] | Natural Gas Basis Derivative [Member] | Basis Swap [Member]
Summary of Significant Accounting Policies (Textual) [Abstract]
Derivative, Swap Type, Average Fixed Price		(0.022)
Fourth Quarter 2021 [Member] | Natural Gas Derivative [Member] | Collar Contracts [Member]
Summary of Significant Accounting Policies (Textual) [Abstract]
Derivative, Nonmonetary Notional Amount | MMBTU		5,311,000
Derivative, Average Floor Price		2.35
Derivative, Average Cap Price		2.76
Fourth Quarter 2021 [Member] | Natural Gas Derivative [Member] | Collar Contracts [Member] | Subsequent Event
Summary of Significant Accounting Policies (Textual) [Abstract]
Derivative, Nonmonetary Notional Amount | MMBTU				1,840,000
Derivative, Average Floor Price				2.95
Derivative, Average Cap Price				3.18
Fourth Quarter 2021 [Member] | Natural Gas Derivative [Member] | Swap [Member]
Summary of Significant Accounting Policies (Textual) [Abstract]
Derivative, Swap Type, Average Fixed Price		2.69
Fourth Quarter 2021 [Member] | Oil Derivative [Member] | Collar Contracts [Member]
Summary of Significant Accounting Policies (Textual) [Abstract]
Derivative, Nonmonetary Notional Amount | MMBTU		84,640
Derivative, Average Floor Price		34.70
Derivative, Average Cap Price		41.01
Fourth Quarter 2021 [Member] | Oil Derivative [Member] | Swap [Member]
Summary of Significant Accounting Policies (Textual) [Abstract]
Derivative, Swap Type, Average Fixed Price | $ / Boe		52.39
Fourth Quarter 2021 [Member] | Oil Basis Calendar Monthly Roll Differential Swap | Basis Swap [Member]
Summary of Significant Accounting Policies (Textual) [Abstract]
Derivative, Nonmonetary Notional Amount | bbl		241,500
Derivative, Swap Type, Average Fixed Price		(0.33)
Fourth Quarter 2021 [Member] | NGL Contract | Swap [Member] | Subsequent Event
Summary of Significant Accounting Policies (Textual) [Abstract]
Derivative, Nonmonetary Notional Amount | bbl				146,324
Derivative, Swap Type, Average Fixed Price | $ / Boe				24.13
First Quarter 2022 | Natural Gas Basis Derivative [Member] | Basis Swap [Member]
Summary of Significant Accounting Policies (Textual) [Abstract]
Derivative, Swap Type, Average Fixed Price		(0.080)
First Quarter 2022 | Natural Gas Basis Derivative [Member] | Basis Swap [Member] | Subsequent Event
Summary of Significant Accounting Policies (Textual) [Abstract]
Derivative, Nonmonetary Notional Amount | MMBTU				900,000
Derivative, Swap Type, Average Fixed Price				(0.030)
First Quarter 2022 | Natural Gas Derivative [Member] | Collar Contracts [Member]
Summary of Significant Accounting Policies (Textual) [Abstract]
Derivative, Nonmonetary Notional Amount | MMBTU		4,415,000
Derivative, Average Floor Price		2.50
Derivative, Average Cap Price		3.35
First Quarter 2022 | Natural Gas Derivative [Member] | Collar Contracts [Member] | Subsequent Event
Summary of Significant Accounting Policies (Textual) [Abstract]
Derivative, Nonmonetary Notional Amount | MMBTU				3,150,000
Derivative, Average Floor Price				2.95
Derivative, Average Cap Price				3.31
First Quarter 2022 | Oil Derivative [Member] | Collar Contracts [Member]
Summary of Significant Accounting Policies (Textual) [Abstract]
Derivative, Nonmonetary Notional Amount | MMBTU		40,500
Derivative, Average Floor Price		40.00
Derivative, Average Cap Price		45.55
First Quarter 2022 | Oil Derivative [Member] | Swap [Member]
Summary of Significant Accounting Policies (Textual) [Abstract]
Derivative, Swap Type, Average Fixed Price | $ / Boe		36.79
First Quarter 2022 | Oil Derivative [Member] | Swap [Member] | Subsequent Event
Summary of Significant Accounting Policies (Textual) [Abstract]
Derivative, Nonmonetary Notional Amount | bbl				45,000
Derivative, Swap Type, Average Fixed Price | $ / Boe				50.00
First Quarter 2022 | Oil Basis Calendar Monthly Roll Differential Swap | Basis Swap [Member]
Summary of Significant Accounting Policies (Textual) [Abstract]
Derivative, Nonmonetary Notional Amount | bbl		90,000
Derivative, Swap Type, Average Fixed Price		(0.12)
First Quarter 2022 | Oil Basis Calendar Monthly Roll Differential Swap | Basis Swap [Member] | Subsequent Event
Summary of Significant Accounting Policies (Textual) [Abstract]
Derivative, Nonmonetary Notional Amount | bbl				90,000
Derivative, Swap Type, Average Fixed Price				0.18
Second Quarter 2022 | Natural Gas Basis Derivative [Member] | Basis Swap [Member]
Summary of Significant Accounting Policies (Textual) [Abstract]
Derivative, Swap Type, Average Fixed Price		(0.080)
Second Quarter 2022 | Natural Gas Basis Derivative [Member] | Basis Swap [Member] | Subsequent Event
Summary of Significant Accounting Policies (Textual) [Abstract]
Derivative, Nonmonetary Notional Amount | MMBTU				910,000
Derivative, Swap Type, Average Fixed Price				(0.030)
Second Quarter 2022 | Natural Gas Derivative [Member] | Collar Contracts [Member]
Summary of Significant Accounting Policies (Textual) [Abstract]
Derivative, Nonmonetary Notional Amount | MMBTU		4,200,000
Derivative, Average Floor Price		2.23
Derivative, Average Cap Price		2.70
Second Quarter 2022 | Oil Derivative [Member] | Collar Contracts [Member]
Summary of Significant Accounting Policies (Textual) [Abstract]
Derivative, Nonmonetary Notional Amount | MMBTU		115,850
Derivative, Average Floor Price		39.25
Derivative, Average Cap Price		46.20
Second Quarter 2022 | Oil Derivative [Member] | Swap [Member] | Subsequent Event
Summary of Significant Accounting Policies (Textual) [Abstract]
Derivative, Nonmonetary Notional Amount | bbl				45,500
Derivative, Swap Type, Average Fixed Price | $ / Boe				50.00
Second Quarter 2022 | Oil Basis Calendar Monthly Roll Differential Swap | Basis Swap [Member]
Summary of Significant Accounting Policies (Textual) [Abstract]
Derivative, Nonmonetary Notional Amount | bbl		91,000
Derivative, Swap Type, Average Fixed Price		(0.12)
Second Quarter 2022 | Oil Basis Calendar Monthly Roll Differential Swap | Basis Swap [Member] | Subsequent Event
Summary of Significant Accounting Policies (Textual) [Abstract]
Derivative, Nonmonetary Notional Amount | bbl				91,000
Derivative, Swap Type, Average Fixed Price				0.18
Third Quarter 2022 | Natural Gas Basis Derivative [Member] | Basis Swap [Member]
Summary of Significant Accounting Policies (Textual) [Abstract]
Derivative, Swap Type, Average Fixed Price		(0.080)
Third Quarter 2022 | Natural Gas Basis Derivative [Member] | Basis Swap [Member] | Subsequent Event
Summary of Significant Accounting Policies (Textual) [Abstract]
Derivative, Nonmonetary Notional Amount | MMBTU				920,000
Derivative, Swap Type, Average Fixed Price				(0.030)
Third Quarter 2022 | Natural Gas Derivative [Member] | Collar Contracts [Member]
Summary of Significant Accounting Policies (Textual) [Abstract]
Derivative, Nonmonetary Notional Amount | MMBTU		3,933,000
Derivative, Average Floor Price		2.39
Derivative, Average Cap Price		2.74
Third Quarter 2022 | Oil Derivative [Member] | Swap [Member]
Summary of Significant Accounting Policies (Textual) [Abstract]
Derivative, Swap Type, Average Fixed Price | $ / Boe		41.58
Third Quarter 2022 | Oil Derivative [Member] | Swap [Member] | Subsequent Event
Summary of Significant Accounting Policies (Textual) [Abstract]
Derivative, Nonmonetary Notional Amount | bbl				46,000
Derivative, Swap Type, Average Fixed Price | $ / Boe				50.00
Third Quarter 2022 | Oil Basis Calendar Monthly Roll Differential Swap | Basis Swap [Member]
Summary of Significant Accounting Policies (Textual) [Abstract]
Derivative, Nonmonetary Notional Amount | bbl		92,000
Derivative, Swap Type, Average Fixed Price		(0.12)
Third Quarter 2022 | Oil Basis Calendar Monthly Roll Differential Swap | Basis Swap [Member] | Subsequent Event
Summary of Significant Accounting Policies (Textual) [Abstract]
Derivative, Nonmonetary Notional Amount | bbl				92,000
Derivative, Swap Type, Average Fixed Price				0.18
Fourth Quarter 2022 | Natural Gas Basis Derivative [Member] | Basis Swap [Member]
Summary of Significant Accounting Policies (Textual) [Abstract]
Derivative, Swap Type, Average Fixed Price		(0.080)
Fourth Quarter 2022 | Natural Gas Basis Derivative [Member] | Basis Swap [Member] | Subsequent Event
Summary of Significant Accounting Policies (Textual) [Abstract]
Derivative, Nonmonetary Notional Amount | MMBTU				920,000
Derivative, Swap Type, Average Fixed Price				(0.030)
Fourth Quarter 2022 | Oil Derivative [Member] | Swap [Member] | Subsequent Event
Summary of Significant Accounting Policies (Textual) [Abstract]
Derivative, Nonmonetary Notional Amount | bbl				46,000
Derivative, Swap Type, Average Fixed Price | $ / Boe				50.00
Fourth Quarter 2022 | Oil Basis Calendar Monthly Roll Differential Swap | Basis Swap [Member]
Summary of Significant Accounting Policies (Textual) [Abstract]
Derivative, Nonmonetary Notional Amount | bbl		92,000
Derivative, Swap Type, Average Fixed Price		(0.12)
Fourth Quarter 2022 | Oil Basis Calendar Monthly Roll Differential Swap | Basis Swap [Member] | Subsequent Event
Summary of Significant Accounting Policies (Textual) [Abstract]
Derivative, Nonmonetary Notional Amount | bbl				92,000
Derivative, Swap Type, Average Fixed Price				0.18
Kinder Morgan Concentration Risk [Member]
Summary of Significant Accounting Policies (Textual) [Abstract]
Concentration Risk, Percentage		19.00%	31.00%
Plains Marketing Concentration Risk [Member]
Summary of Significant Accounting Policies (Textual) [Abstract]
Concentration Risk, Percentage		17.00%	14.00%
Twin Eagle Concentration Risk [Member]
Summary of Significant Accounting Policies (Textual) [Abstract]
Concentration Risk, Percentage		17.00%	13.00%
Shell Trading Concentration Risk [Member]
Summary of Significant Accounting Policies (Textual) [Abstract]
Concentration Risk, Percentage			11.00%
Trafigura US
Summary of Significant Accounting Policies (Textual) [Abstract]
Concentration Risk, Percentage		13.00%
Minimum [Member]
Summary of Significant Accounting Policies (Textual) [Abstract]
Property, Plant and Equipment, Useful Life		2 years
Maximum [Member]
Summary of Significant Accounting Policies (Textual) [Abstract]
Property, Plant and Equipment, Useful Life		20 years
Oil sales [Member]
Summary of Significant Accounting Policies (Textual) [Abstract]
Revenue from Contract with Customer, Excluding Assessed Tax | $		$ 57,651	$ 92,833
Natural gas sales [Member]
Summary of Significant Accounting Policies (Textual) [Abstract]
Revenue from Contract with Customer, Excluding Assessed Tax | $		105,234	170,558
NGL sales [Member]
Summary of Significant Accounting Policies (Textual) [Abstract]
Revenue from Contract with Customer, Excluding Assessed Tax | $		$ 14,500	$ 25,241