Property and Equipment (Details Textual)	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2018 USD ($) USD_Bbl	Jun. 30, 2017 USD ($) USD_Bbl	Jun. 30, 2018 USD ($) USD_Bbl	Jun. 30, 2017 USD ($) USD_Bbl	Dec. 31, 2017 USD ($)
Property and Equipment (Textual)
Capitalized overhead	$ 119,000	$ 56,000	$ 190,000	$ 131,000
Depletion expense related to oil and gas properties	$ 1,800,000	$ 539,000	$ 3,100,000	$ 1,100,000
Depletion expense related to oil and gas properties (in dollars per Mcfe) | USD_Bbl	0.77	0.40	0.80	0.41
Depreciation, depletion and amortization	$ 1,979,000	$ 662,000	$ 3,471,000	$ 1,234,000
Unproved properties not subject to depletion [Member]
Property and Equipment (Textual)
Depletion expense related to oil and gas properties			$ 3,500,000		$ 1,900,000