Supplemental Schedules of Oil and Gas Information - Working Interest Reserve Quantity Information (Details) - bbl	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Oil and Condensate (Bbls) [Member]
Beginning of Year (Barrel of Oil)	376,396	401,584
Revisions of Previous Estimates (Barrel of Oil)	26,063	18,951
Extensions and Discoveries (Barrel of Oil)	13,699	16,405
Purchase of Reserves (Barrel of Oil)
Production (Barrel of Oil)	(52,960)	(60,544)
End of Year (Barrel of Oil)	363,198	376,396
Beginning of Year (Barrel of Oil)	341,152	358,822
End of Year (Barrel of Oil)	326,752	341,152
Gas (MCF) [Member]
Beginning of Year (Barrel of Oil)	3,191,511	3,023,754
Revisions of Previous Estimates (Barrel of Oil)	75,610	494,665
Extensions and Discoveries (Barrel of Oil)	8,094	190,923
Purchase of Reserves (Barrel of Oil)
Production (Barrel of Oil)	(443,354)	(517,831)
End of Year (Barrel of Oil)	2,831,861	3,191,511
Beginning of Year (Barrel of Oil)	2,944,804	2,809,944
End of Year (Barrel of Oil)	2,576,738	2,944,804