Derivative Instruments - Effect of Derivative Instruments on the Condensed Consolidated Balance Sheet (Details) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Effect of derivative instruments on the Consolidated Balance Sheet
Derivative Assets	$ 40,636	$ 31
Derivative Liabilities	0	9
Derivatives not designated as hedges | Commodity contracts
Effect of derivative instruments on the Consolidated Balance Sheet
Derivative Assets	40,636	31
Derivative Liabilities	0	9
Derivative instruments (current) | Derivatives not designated as hedges | Commodity contracts
Effect of derivative instruments on the Consolidated Balance Sheet
Derivative Assets	40,636	31
Derivative Liabilities	0	0
Accrued liabilities (current) | Derivatives not designated as hedges | Commodity contracts
Effect of derivative instruments on the Consolidated Balance Sheet
Derivative Assets	0	0
Derivative Liabilities	$ 0	$ 9