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Revenue Recognition - Additional Information (Detail) - Vessel Mobilization $ in Millions	Mar. 31, 2018 USD ($)
Disaggregation Of Revenue [Line Items]
Deferred costs included within other current assets	$ 0.4
Deferred capital modification revenue included within other current liabilities	$ 1.9

X

- Definition

Amount of deferred cost assets and assets classified as other.

+ References

No definition available.

+ Details

Name:	us-gaap_DeferredCostsAndOtherAssets
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

X

- Definition

Carrying amount as of the balance sheet date of unearned revenue or income, not otherwise specified in the taxonomy, which is expected to be taken into income during the current period and current obligations not separately disclosed in the balance sheet (other liabilities, current).

+ References

No definition available.

+ Details

Name:	us-gaap_DeferredCreditsAndOtherLiabilitiesCurrent
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

X

- 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.

+ Details

Name:	us-gaap_DisaggregationOfRevenueLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

X

- Details

Name:	us-gaap_ProductOrServiceAxis=tdw_VesselMobilizationMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: