Investments in Affiliates (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance, Investments	$ 14,267	$ 668
Investment in affiliates gain	7,734	1,128
Cash distributions	(125)	(68)
Cash contributions		6,865
Class B Units issuance		2,778
Appalachia Warrant exercise		2,896
California Warrant exercise	(1,854)
OIE Membership Acquisition	(12,801)
Ending balance, Investments	598	14,267
Carbon California [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance, Investments	1,854
Investment in affiliates gain
Cash distributions
Cash contributions
Class B Units issuance		1,854
Appalachia Warrant exercise
California Warrant exercise	(1,854)
Ending balance, Investments		1,854
Carbon Appalachia [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance, Investments	11,775
Investment in affiliates gain	1,026	1,090
Cash distributions
Cash contributions		6,865
Class B Units issuance		924
Appalachia Warrant exercise		2,896
California Warrant exercise
OIE Membership Acquisition	(12,801)
Ending balance, Investments		11,775
Other [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance, Investments	638	668
Investment in affiliates gain	85	38
Cash distributions	(125)	(68)
Cash contributions
Class B Units issuance
Ending balance, Investments	$ 598	$ 638