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Summary of Vessels Impaired and Amount of Impairment Incurred (Parenthetical) (Detail) - USD ($) $ in Thousands | 1 Months Ended | 3 Months Ended | 4 Months Ended | 5 Months Ended | 12 Months Ended
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Jul. 31, 2017 | Dec. 31, 2017 | Jun. 30, 2017 | Mar. 31, 2017 | Dec. 31, 2016 | Sep. 30, 2016 | Jun. 30, 2016 | Jul. 31, 2017 | [1] | Dec. 31, 2017 | Mar. 31, 2017
Schedule of Vessels Impaired and Amount of Impairment Incurred [Line Items] |  |  |  |  |  |  |  |  |  |  |  |
Asset impairments |  | $ 16,777 |  |  |  |  |  |  | $ 16,777 | [1] |  |
Predecessor |  |  |  |  |  |  |  |  |  |  |  |
Schedule of Vessels Impaired and Amount of Impairment Incurred [Line Items] |  |  |  |  |  |  |  |  |  |  |  |
Asset impairments | $ 21,325 |  | $ 163,423 | $ 64,857 | $ 253,422 | $ 129,562 | $ 36,886 | $ 184,748 |  |  | $ 484,727 | [1]
Inventory and other non-vessel assets. |  |  |  |  |  |  |  |  |  |  |  |
Schedule of Vessels Impaired and Amount of Impairment Incurred [Line Items] |  |  |  |  |  |  |  |  |  |  |  |
Asset impairments |  |  |  |  |  |  |  |  | $ 2,300 |  |  |
Inventory and other non-vessel assets. | Predecessor |  |  |  |  |  |  |  |  |  |  |  |
Schedule of Vessels Impaired and Amount of Impairment Incurred [Line Items] |  |  |  |  |  |  |  |  |  |  |  |
Asset impairments |  |  |  |  |  |  |  |  |  |  | $ 2,200 |
[1] | The period August 1, 2017 through December 31, 2017 and the year ended March 31, 2017 included $2.3 million and $2.2 million, respectively, of impairments related to inventory and other non-vessel assets.

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- Definition Amount of write-down of assets recognized in the income statement. Includes, but is not limited to, losses from tangible assets, intangible assets and goodwill. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 28 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=109223946&loc=d3e3602-108585 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 360 -SubTopic 10 -Section 45 -Paragraph 4 -URI http://asc.fasb.org/extlink&oid=109226348&loc=d3e2420-110228 + Details
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