Fair Value Measurements (Details) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Credit risk valuation adjustment	$ 200	$ 200
Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total commodity derivative assets	533	570
Total commodity derivative liabilities	(11,690)	(20,438)
Recurring | Non-trading commodity derivative
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total commodity derivative assets	459	401
Total commodity derivative liabilities	(11,690)	(20,438)
Recurring | Trading commodity derivative
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total commodity derivative assets	74	169
Total commodity derivative liabilities	0	0
Recurring | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total commodity derivative assets	19	0
Total commodity derivative liabilities	0	(1,666)
Recurring | Level 1 | Non-trading commodity derivative
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total commodity derivative assets	19	0
Total commodity derivative liabilities	0	(1,666)
Recurring | Level 1 | Trading commodity derivative
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total commodity derivative assets	0	0
Total commodity derivative liabilities	0	0
Recurring | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total commodity derivative assets	514	570
Total commodity derivative liabilities	(11,690)	(18,772)
Recurring | Level 2 | Non-trading commodity derivative
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total commodity derivative assets	440	401
Total commodity derivative liabilities	(11,690)	(18,772)
Recurring | Level 2 | Trading commodity derivative
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total commodity derivative assets	74	169
Total commodity derivative liabilities	0	0
Recurring | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total commodity derivative assets	0	0
Total commodity derivative liabilities	0	0
Recurring | Level 3 | Non-trading commodity derivative
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total commodity derivative assets	0	0
Total commodity derivative liabilities	0	0
Recurring | Level 3 | Trading commodity derivative
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total commodity derivative assets	0	0
Total commodity derivative liabilities	$ 0	$ 0