Information Regarding Proved Oil and Gas Reserves (Details 2) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Increase (Decrease) in Standardized Measure of Discounted Future Net Cash Flow Relating to Proved Oil and Gas Reserves [Roll Forward]
Beginning of the period	$ 216,393	$ 141,427	$ 39,797
Sales of oil and gas production during the period, net of production costs	(47,292)	(29,939)	(8,041)
Acquisitions and divestitures	35,182		81,066
Net change in prices and production costs	(1,345)	35,537	2,974
Changes in estimated future development costs			(8,561)
Extensions, discoveries and improved recovery			231
Revisions of previous quantity estimates, estimated timing of development and other	53,919	38,038	17,137
Previously estimated development and abandonment costs incurred during the period	40,736	17,187	12,805
Accretion of discount	21,639	14,143	4,019
End of period	319,232	216,393	141,427
Company
Increase (Decrease) in Standardized Measure of Discounted Future Net Cash Flow Relating to Proved Oil and Gas Reserves [Roll Forward]
Beginning of the period	572	285	192
Sales of oil and gas production during the period, net of production costs	(127)	(28)	(62)
Acquisitions and divestitures	0		0
Net change in prices and production costs	20	(60)	(20)
Changes in estimated future development costs			14
Extensions, discoveries and improved recovery			0
Revisions of previous quantity estimates, estimated timing of development and other	(392)	346	142
Previously estimated development and abandonment costs incurred during the period	0	0	0
Accretion of discount	57	29	19
End of period	130	572	285
Company's Share of Laramie Energy
Increase (Decrease) in Standardized Measure of Discounted Future Net Cash Flow Relating to Proved Oil and Gas Reserves [Roll Forward]
Beginning of the period	215,821	141,142	39,605
Sales of oil and gas production during the period, net of production costs	(47,165)	(29,911)	(7,979)
Acquisitions and divestitures	35,182		81,066
Net change in prices and production costs	(1,365)	35,597	2,994
Changes in estimated future development costs			(8,575)
Extensions, discoveries and improved recovery			231
Revisions of previous quantity estimates, estimated timing of development and other	54,311	37,692	16,995
Previously estimated development and abandonment costs incurred during the period	40,736	17,187	12,805
Accretion of discount	21,582	14,114	4,000
End of period	$ 319,102	$ 215,821	$ 141,142