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Acquisitions, Investments and Dispositions - Mountain Valley Pipeline (Details) - CET Gas - Mountain Valley Pipeline - USD ($) $ in Millions | 1 Months Ended |  |
--- | --- | --- | ---
Jan. 31, 2016 | Dec. 31, 2019 | Dec. 31, 2018
Schedule of Equity Method Investments [Line Items] |  |  |
Percentage of equity interest acquired | 12.50% | 12.50% |
Payments to acquire equity interest | $ 18 |  |
Equity method investment |  | $ 530 | $ 337
Expected reduction in equity interest |  | 10.00% |
Minimum |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |
Estimated project cost |  | $ 5,300 |
Maximum |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |
Equity method investment |  | 530 |
Estimated project cost |  | $ 5,500 |

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