Fair Value - Unobservable Inputs Related to our Level 3 Liabilities (Details) - Natural Gas Fixed Price Forward Contracts - Level 3 $ in Thousands	Dec. 31, 2020 USD ($) $ / MMBTU
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Derivative liabilities | $	$ 2,574
Minimum | Measurement Input, Commodity Forward Price | Valuation Technique, Discounted Cash Flow
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Derivative measurement input	2.82
Maximum | Measurement Input, Commodity Forward Price | Valuation Technique, Discounted Cash Flow
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Derivative measurement input	5.03
Weighted Average | Measurement Input, Commodity Forward Price | Valuation Technique, Discounted Cash Flow
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Derivative measurement input	3.67