Information Regarding Proved Oil and Gas Reserves (Details 2) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Increase (Decrease) in Standardized Measure of Discounted Future Net Cash Flow Relating to Proved Oil and Gas Reserves [Roll Forward]
Beginning of the period	$ 40,193	$ 172,365	$ 92,862
Sales of oil and gas production during the period, net of production costs	(8,041)	(6,232)	(5,051)
Acquisitions and divestitures	81,066	(4,789)
Net change in prices and production costs	2,974	(154,243)	35,806
Changes in estimated future development costs	(8,561)	796	(6,174)
Extensions, discoveries and improved recovery	231	9,273	4,999
Revisions of previous quantity estimates, estimated timing of development and other	18,492	(9,222)	26,521
Previously estimated development and abandonment costs incurred during the period	12,805	15,008	14,115
Other	0
Accretion of discount	4,019	17,237	9,287
End of period	143,178	40,193	172,365
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	192	1,766	3,537
Sales of oil and gas production during the period, net of production costs	(62)	(479)	(1,288)
Acquisitions and divestitures	0	0
Net change in prices and production costs	(20)	(679)	(31)
Changes in estimated future development costs	14	8	118
Extensions, discoveries and improved recovery	0	0	85
Revisions of previous quantity estimates, estimated timing of development and other	142	(601)	(1,111)
Previously estimated development and abandonment costs incurred during the period	0	0	102
Other	0
Accretion of discount	19	177	354
End of period	285	192	1,766
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	40,001	170,599	89,325
Sales of oil and gas production during the period, net of production costs	(7,979)	(5,753)	(3,763)
Acquisitions and divestitures	81,066	(4,789)
Net change in prices and production costs	2,994	(153,564)	35,837
Changes in estimated future development costs	(8,575)	788	(6,292)
Extensions, discoveries and improved recovery	231	9,273	4,914
Revisions of previous quantity estimates, estimated timing of development and other	18,350	(8,621)	27,632
Previously estimated development and abandonment costs incurred during the period	12,805	15,008	14,013
Other	0
Accretion of discount	4,000	17,060	8,933
End of period	$ 142,893	$ 40,001	$ 170,599