Fair Value Measurements - Fair Value Recognition - Liabilities (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Reconciliation of the beginning and ending balances of liabilities measured at fair value using significant unobservable inputs (Level 3)
Fair Value, Liability, Recurring Basis, Still Held, Unrealized Gain (Loss), Statement of Income [Extensible List]	Unrealized Gain (Loss) on Commodity Contracts	Unrealized Gain (Loss) on Commodity Contracts	Unrealized Gain (Loss) on Commodity Contracts	Unrealized Gain (Loss) on Commodity Contracts
Commodity swap contracts
Reconciliation of the beginning and ending balances of liabilities measured at fair value using significant unobservable inputs (Level 3)
Beginning Balance			$ (164)
Settlements, net			56
Total gain (loss)			108
Change in unrealized gain (loss) included in earnings			164
Embedded derivatives
Reconciliation of the beginning and ending balances of liabilities measured at fair value using significant unobservable inputs (Level 3)
Beginning Balance	$ (3,308)		(81)
Total gain (loss)	1,384		(1,843)
Ending Balance	(1,924)		(1,924)
Change in unrealized gain (loss) included in earnings	1,384		(1,843)
Warrants
Reconciliation of the beginning and ending balances of liabilities measured at fair value using significant unobservable inputs (Level 3)
Beginning Balance	(445)	$ (2,693)	40	$ (1,079)
Total gain (loss)	445	17	40	(1,597)
Ending Balance		(2,676)		(2,676)
Change in unrealized gain (loss) included in earnings	$ 445	$ 17	$ 40	$ (1,597)