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Interim Financial Statements - Additional Information (Detail) - GulfMark | 3 Months Ended | 6 Months Ended
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Jun. 30, 2019 | Jun. 30, 2019
Interim Financial Statements [Line Items] |  |
Business acquisition, name of acquired entity | GulfMark Offshore, Inc. | GulfMark Offshore, Inc.
Business acquisition, effective date of acquisition | Nov. 15, 2018 | Nov. 15, 2018
Business acquisition, date of acquisition agreement | Jul. 15, 2018 | Jul. 15, 2018

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- Definition Date when the business acquisition agreement was executed, in CCYY-MM-DD format. + References No definition available. + Details
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