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Summary of Norwegian Kroner (NOK) Denominated Borrowings Outstanding (Detail) kr in Thousands, $ in Thousands	Jun. 30, 2018 USD ($)	Dec. 31, 2017 NOK (kr)	Dec. 31, 2017 USD ($)	Mar. 31, 2017 NOK (kr)	Mar. 31, 2017 USD ($)
Debt [Line Items]
Amount outstanding	$ 436,403		$ 438,827
Troms Offshore Supply AS | January 2014 notes
Debt [Line Items]
Amount outstanding		kr 212,500	25,965
Fair value in U.S. dollar equivalent			25,850
Troms Offshore Supply AS | May 2012 notes
Debt [Line Items]
Amount outstanding		kr 115,020	14,054
Fair value in U.S. dollar equivalent			$ 14,013
Predecessor
Debt [Line Items]
Fair value in U.S. dollar equivalent					$ 280,000
Predecessor | Troms Offshore Supply AS | January 2014 notes
Debt [Line Items]
Amount outstanding				kr 225,000	26,167
Fair value in U.S. dollar equivalent					26,133
Predecessor | Troms Offshore Supply AS | May 2012 notes
Debt [Line Items]
Amount outstanding				kr 127,800	14,864
Fair value in U.S. dollar equivalent					$ 14,793

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Fair value portion of debt instrument payable, including, but not limited to, notes payable and loans payable.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
-Paragraph 10
-URI http://asc.fasb.org/extlink&oid=109250915&loc=d3e13433-108611

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+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
-Section 50
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-Name Accounting Standards Codification
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