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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
	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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Schedule of combined fair value of assets that incurred impairments.

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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

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