Summary of Significant Accounting Policies (Details Textual) $ in Thousands	12 Months Ended
	Dec. 31, 2018 USD ($) shares	Dec. 31, 2017 USD ($) shares	Dec. 22, 2017
Summary of Significant Accounting Policies (Textual) [Abstract]
Total capitalized internal costs	$ 4,500	$ 4,600
Discount rate for estimated future net revenues from proved properties	10.00%
Write-down of oil and gas properties	$ 0	0
Allowance for doubtful accounts receivable, current	100	100
Accounts receivable from oil and gas sales	36,900	20,100
Accounts receivable related to joint interest owners	5,600	2,100
Severance tax credit receivables	2,400	2,100
Other receivables	$ 1,600	3,000
Percentage of working interest in wells	100.00%
Total amount of supervision fees charged to wells	$ 4,600	4,700
Previous Federal Corporate Tax Rate			0.35
New Federal Corporate Tax Rate			0.21
Restricted Cash	$ 0	$ 220
Concentration risk, percentage		10.00%
Treasury Stock, Shares, Acquired | shares	15,107	28,279
Operating Lease, Right-of-Use Asset	$ 3,000
Kinder Morgan Concentration Risk [Member]
Summary of Significant Accounting Policies (Textual) [Abstract]
Concentration risk, percentage	37.00%	48.00%
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