Recently Issued Accounting Standards (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Disaggregation of Revenue [Line Items]
Revenue receivable	$ 6,814		$ 6,814		$ 15,340
Revenue	20,886	$ 28,184	67,310	$ 73,207
Oil production
Disaggregation of Revenue [Line Items]
Revenue receivable	1,800		1,800
Revenue	5,211	7,107	17,138	21,278
Natural gas production
Disaggregation of Revenue [Line Items]
Revenue receivable	3,500		3,500
Revenue	11,344	16,428	38,054	40,841
Natural gas liquids production
Disaggregation of Revenue [Line Items]
Revenue receivable	1,500		1,500
Revenue	$ 4,331	$ 4,649	$ 12,118	$ 11,088
Minimum
Disaggregation of Revenue [Line Items]
Revenue recognized, period			1 month
Maximum
Disaggregation of Revenue [Line Items]
Revenue recognized, period			2 months