Fair Value Measurements - Fair Value Recognition - Assets (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Reconciliation of the beginning and ending balances of assets measured at fair value using significant unobservable inputs (Level 3)
Fair Value, Asset, Recurring Basis, Still Held, Unrealized Gain (Loss), Statement of Income [Extensible List]	Revenue from Contract with Customer, Excluding Assessed Tax	Revenue from Contract with Customer, Excluding Assessed Tax
Commodity swap contracts
Reconciliation of the beginning and ending balances of assets measured at fair value using significant unobservable inputs (Level 3)
Beginning balance	$ 3,270	$ 10,332
Settlements, net	(24)
Total gain (loss)	9,299	(4,970)
Ending balance	12,545	5,362
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)	9,275	$ (4,970)
Embedded derivatives
Reconciliation of the beginning and ending balances of assets measured at fair value using significant unobservable inputs (Level 3)
Beginning balance	723
Total gain (loss)	(580)
Ending balance	143
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)	$ (580)