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Disclosure of Accounted Total Revenues Percentage (Detail) - Sales Revenue, Net - Customer Concentration Risk | 4 Months Ended | 5 Months Ended | 12 Months Ended
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Jul. 31, 2017 | Dec. 31, 2017 | Mar. 31, 2017
Chevron Corporation |  |  |  |
Entity Wide Revenue Major Customer [Line Items] |  |  |  |
Total revenue percentage |  |  | 17.40% |
Chevron Corporation | Predecessor |  |  |  |
Entity Wide Revenue Major Customer [Line Items] |  |  |  |
Total revenue percentage |  | 17.50% |  | 16.30%
Freeport McMoRan | Predecessor |  |  |  |
Entity Wide Revenue Major Customer [Line Items] |  |  |  |
Total revenue percentage | [1] |  |  | 11.30%
Saudi Aramco |  |  |  |
Entity Wide Revenue Major Customer [Line Items] |  |  |  |
Total revenue percentage |  |  | 10.10% |
Saudi Aramco | Predecessor |  |  |  |
Entity Wide Revenue Major Customer [Line Items] |  |  |  |
Total revenue percentage |  | 11.70% |  | 10.00%
[1] | A significant portion of this customer's year ended March 31, 2017 revenue was the result of the early termination of a long-term vessel charter contract.

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