Derivative Instruments - Offsetting Assets (Details) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Total Derivative Assets
Offsetting Assets [Line Items]
Gross Assets	$ 2,547	$ 1,073
Gross Amounts Offset	(2,014)	(503)
Net Assets	533	570
Cash Collateral Offset	0	0
Net Amount Presented	533	570
Total Current Derivative Assets
Offsetting Assets [Line Items]
Gross Assets	1,601	740
Gross Amounts Offset	(1,289)	(276)
Net Assets	312	464
Cash Collateral Offset	0	0
Net Amount Presented	312	464
Non-trading commodity derivatives
Offsetting Assets [Line Items]
Gross Assets	1,526	570
Gross Amounts Offset	(1,288)	(275)
Net Assets	238	295
Cash Collateral Offset	0	0
Net Amount Presented	238	295
Trading commodity derivatives
Offsetting Assets [Line Items]
Gross Assets	75	170
Gross Amounts Offset	(1)	(1)
Net Assets	74	169
Cash Collateral Offset	0	0
Net Amount Presented	74	169
Total Non-current Derivative Assets
Offsetting Assets [Line Items]
Gross Assets	946	333
Gross Amounts Offset	(725)	(227)
Net Assets	221	106
Cash Collateral Offset	0	0
Net Amount Presented	221	106
Non-trading commodity derivatives
Offsetting Assets [Line Items]
Gross Assets	946	333
Gross Amounts Offset	(725)	(227)
Net Assets	221	106
Cash Collateral Offset	0	0
Net Amount Presented	221	106
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