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Summary of Norwegian Kroner (NOK) Denominated Borrowings Outstanding (Parenthetical) (Detail) - Troms Offshore Supply AS	9 Months Ended	12 Months Ended
	Dec. 31, 2017	Mar. 31, 2017
January 2014 notes
Debt [Line Items]
Debt Instrument Maturity Period	January 2014
January 2014 notes | Predecessor
Debt [Line Items]
Debt Instrument Maturity Period		January 2014
May 2012 notes
Debt [Line Items]
Debt Instrument Maturity Period	May 2012
May 2012 notes | Predecessor
Debt [Line Items]
Debt Instrument Maturity Period		May 2012

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

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- Definition

Description of the maturity date of the debt instrument including whether the debt matures serially and, if so, a brief description of the serial maturities.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22(a)(2))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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