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Related Party Transactions (Details) - USD ($) $ in Millions | 3 Months Ended | 9 Months Ended
--- | --- | ---
Sep. 30, 2021 | Sep. 30, 2020 | Sep. 30, 2021 | Sep. 30, 2020
Black Warrior Methane (BWM) |  |  |  |
Related Party Transaction [Line Items] |  |  |  |
Proportionate consolidation method, ownership percentage | 50.00% |  | 50.00% |
Black Warrior Transmission (BWT) |  |  |  |
Related Party Transaction [Line Items] |  |  |  |
Equity method investment, ownership percentage | 50.00% |  | 50.00% |
Allocated Expenses to Joint Venture | Corporate Joint Venture |  |  |  |
Related Party Transaction [Line Items] |  |  |  |
Expenses from transactions with related party | $ 0.4 | $ 0.6 | $ 1.7 | $ 1.9

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