Supplemental Oil and Gas Disclosures Capitalized Costs (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Company
Proved properties	$ 400	$ 400
Company
Company
Unproved properties	0	0
Proved properties	400	400
Oil and Gas Property, Successful Effort Method, Gross, Total	400	400
Accumulated depreciation and depletion	(293)	(275)
Oil and gas property, successful efforts method	107	125
Company's Share of Laramie Energy
Company
Unproved properties	16,379	13,728
Proved properties	473,763	382,789
Oil and Gas Property, Successful Effort Method, Gross, Total	490,142	396,517
Accumulated depreciation and depletion	(150,075)	(111,119)
Oil and gas property, successful efforts method	$ 340,067	$ 285,398