Credit Facilities and Notes Payable (Details Textual) $ in Thousands				3 Months Ended	6 Months Ended
	Feb. 01, 2019 USD ($)	Dec. 31, 2018 USD ($)	Aug. 15, 2017 USD ($)	Jun. 30, 2019 USD ($)	Jun. 30, 2019 USD ($)	Jun. 30, 2018 USD ($)
Credit Facilities and Notes Payable (Textual)
Senior secured asset-based revolving credit facility			$ 8,000		$ 4,029	$ 31,502
Amortization of deferred issuance costs					405	247
Paid in kind interest					1,244
One-time principal reduction payment					$ 13,185	$ 14
Carbon Appalachia [Member]
Credit Facilities and Notes Payable (Textual)
Credit facility			$ 22,000
Old Ironsides Note [Member] | Carbon Appalachia [Member]
Credit Facilities and Notes Payable (Textual)
Bank credit facility, terms		5 years
Amount of unsecured notes issuance		$ 25,100
Interest rate (as a percent)		10.00%
Number of monthly installments					24
One-time principal reduction payment	$ 2,000
Old Ironsides Note [Member] | Carbon Appalachia [Member] | Payment in Kind (PIK) Note [Member]
Credit Facilities and Notes Payable (Textual)
Interest rate (as a percent)				12.00%	12.00%
Paid in kind interest					$ 1,200
2018 Credit Facility [Member] | Carbon Appalachia [Member]
Credit Facilities and Notes Payable (Textual)
Unamortized deferred issuance costs				$ 564	564
Unamortized debt discount, term note				90	90
Senior secured asset-based revolving credit facility					$ 500
Commitment fee (as a percent)					0.50%
Origination fee (as a percent)					0.50%
Credit facility				75,000	$ 75,000
Additional borrowing capacity available				3,800	$ 3,800
Debt Instrument, covenant, ratio of debt to EBITDAX					3.5
Debt Instrument, covenant, current ratio					1.0
Credit facility-revolver outstanding				71,200	$ 71,200
Amortization of deferred issuance costs				$ 63	125
Revolving credit facility maturing date				Dec. 31, 2022
Cash and cash equivalents of borrowers not to exceed				$ 3,000	3,000
Debt issuance costs paid, revolver and term loan				779	779
Debt issuance costs paid, term loan				134	134
Term loan				$ 15,000	$ 15,000
Interest rate (as a percent)				6.25%	6.25%
Number of monthly installments					18
2018 Credit Facility [Member] | Carbon Appalachia [Member] | Minimum [Member] | Base rate [Member]
Credit Facilities and Notes Payable (Textual)
Spread on variable base rate (as a percent)					0.25%
2018 Credit Facility [Member] | Carbon Appalachia [Member] | Minimum [Member] | London interbank offered rate [Member]
Credit Facilities and Notes Payable (Textual)
Spread on variable base rate (as a percent)					2.75%
2018 Credit Facility [Member] | Carbon Appalachia [Member] | Maximum [Member] | Base rate [Member]
Credit Facilities and Notes Payable (Textual)
Spread on variable base rate (as a percent)					0.75%
2018 Credit Facility [Member] | Carbon Appalachia [Member] | Maximum [Member] | London interbank offered rate [Member]
Credit Facilities and Notes Payable (Textual)
Spread on variable base rate (as a percent)					3.75%