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Commitment and Contingencies (Repairs to U.S. Flagged Vessels Operating Abroad) - Additional Information (Detail) | 6 Months Ended | 9 Months Ended
--- | --- | ---
Jun. 30, 2018 | Dec. 31, 2017
Commitments and Contingencies Disclosure [Abstract] |  |
Percentage of vessel repair duty | 50.00% | 50.00%

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- Definition Percentage of custom duty for vessel repair. + References No definition available. + Details
Name: | tdw_PercentageOfCustomDutyForVesselRepair
Namespace Prefix: | tdw_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

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