Derivative Instruments - Offsetting Assets (Details) - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Total Derivative Assets
Offsetting Assets [Line Items]
Gross Assets	$ 24,164	$ 420
Gross Amounts Offset	(6,111)	(109)
Net Assets	18,053	311
Cash Collateral Offset	(456)	0
Net Amount Presented	17,597	311
Total Current Derivative Assets
Offsetting Assets [Line Items]
Gross Assets	22,845	420
Gross Amounts Offset	(5,861)	(109)
Net Assets	16,984	311
Cash Collateral Offset	(456)	0
Net Amount Presented	16,528	311
Non-trading commodity derivatives
Offsetting Assets [Line Items]
Gross Assets	22,826	308
Gross Amounts Offset	(5,861)	(105)
Net Assets	16,965	203
Cash Collateral Offset	(456)	0
Net Amount Presented	16,509	203
Trading commodity derivatives
Offsetting Assets [Line Items]
Gross Assets	19	112
Gross Amounts Offset	0	(4)
Net Assets	19	108
Cash Collateral Offset	0	0
Net Amount Presented	19	108
Total Non-current Derivative Assets
Offsetting Assets [Line Items]
Gross Assets	1,319	0
Gross Amounts Offset	(250)	0
Net Assets	1,069	0
Cash Collateral Offset	0	0
Net Amount Presented	1,069	0
Non-trading commodity derivatives
Offsetting Assets [Line Items]
Gross Assets	1,319	0
Gross Amounts Offset	(250)	0
Net Assets	1,069	0
Cash Collateral Offset	0	0
Net Amount Presented	1,069	0
Trading commodity derivatives
Offsetting Assets [Line Items]
Gross Assets	0	0
Gross Amounts Offset	0	0
Net Assets	0	0
Cash Collateral Offset	0	0
Net Amount Presented	$ 0	$ 0