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Investments & NCI Sherwood Midstream (Details) bbl / d in Thousands, $ in Millions |  | 3 Months Ended |
--- | --- | --- | ---
Jan. 01, 2017 USD ($) bbl / d | Mar. 31, 2018 USD ($) | Mar. 31, 2017 USD ($) | [1] | Dec. 31, 2017 USD ($)
Schedule of Equity Method Investments [Line Items] |  |  |  |
Contribution of fixed assets to joint venture |  | $ 0 | $ 328 |
Equity method investments |  | $ 4,033 |  | $ 4,010
Sherwood Midstream |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |
Equity method investment, ownership percentage |  | 50.00% |  |
Contribution of fixed assets to joint venture | $ 134 |  |  |
Payments to acquire interest in joint venture | $ 20 |  |  |
Equity method investments |  | $ 260 |  | $ 236
MarkWest Ohio Fractionation Company, L.L.C. [Member] |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |
Capacity | bbl / d | 20 |  |  |
Sherwood Midstream | MarkWest Ohio Fractionation Company, L.L.C. [Member] |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |
Payments to acquire interest in joint venture | $ 126 |  |  |
Antero Midstream Partners L.P. [Member] | Sherwood Midstream |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |
Payments to acquire interest in joint venture | $ 154 |  |  |
[1] | Contribution of assets to Sherwood Midstream and Sherwood Midstream Holdings. See Note 5.

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