Property and Equipment (Details Textual) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2019 USD ($) Per_Mcf	Mar. 31, 2018 USD ($) Per_Mcf	Dec. 31, 2018 USD ($)
Property and Equipment (Textual)
Capitalized overhead	$ 68	$ 71
Depletion expense related to oil and gas properties	$ 3,500	$ 1,300
Depletion expense related to oil and gas properties (in dollars per Mcfe) | Per_Mcf	0.54	0.82
Unproved Properties Not Subject To Depletion [Member]
Property and Equipment (Textual)
Depletion expense related to oil and gas properties	$ 5,400		$ 5,400