Fair Value Measurements - Fair Value Recognition - Liabilities (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Commodity swap contracts
Reconciliation of the beginning and ending balances of liabilities measured at fair value using significant unobservable inputs (Level 3)
Total gain (loss)	$ (164)
Ending Balance	(164)
Fair Value, Liabilities Measured on Recurring Basis, Change in Unrealized Gain (Loss)	(164)
Embedded derivatives
Reconciliation of the beginning and ending balances of liabilities measured at fair value using significant unobservable inputs (Level 3)
Total gain (loss)	(81)
Ending Balance	(81)
Fair Value, Liabilities Measured on Recurring Basis, Change in Unrealized Gain (Loss)	(81)
Warrants
Reconciliation of the beginning and ending balances of liabilities measured at fair value using significant unobservable inputs (Level 3)
Beginning Balance	(1,079)	$ 536
Total gain (loss)	1,039	(543)
Ending Balance	(40)	(1,079)
Fair Value, Liabilities Measured on Recurring Basis, Change in Unrealized Gain (Loss)	$ 1,039	$ (543)