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Fair Value Measurements - Additional Information (Detail) | 6 Months Ended
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Jun. 30, 2018
Fair Value Disclosures [Abstract] |
Cash equivalents maturity period, days | 90 days

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- Definition Short term deposits maximum maturity period. + References No definition available. + Details
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Namespace Prefix: | tdw_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

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- References No definition available. + Details
Name: | us-gaap_FairValueDisclosuresAbstract
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration