Costs related to recertification of vessels deferred and amortized, period.

No definition available.

Name:	tdw_CostsRelatedToRecertificationOfVesselsDeferredAndAmortizedPeriod
Namespace Prefix:	tdw_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Planned major maintenance activities, comprehensive surveys to maintain certifications for vessels, consecutive period.

+ References

No definition available.

+ Details

Name:	tdw_PlannedMajorMaintenanceActivitiesComprehensiveSurveysToMaintainCertificationsForVesselsConsecutivePeriod
Namespace Prefix:	tdw_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Reorganizations.

+ References

No definition available.

+ Details

Name:	tdw_ReorganizationsLineItems
Namespace Prefix:	tdw_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

United States Bankruptcy Court where petition for bankruptcy was filed.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 852
-SubTopic 10
-Section 55
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=84165509&loc=d3e56145-112766

+ Details

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

- Definition

Date the plan of reorganization is filed with the bankruptcy court, in CCYY-MM-DD format.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 852
-SubTopic 10
-Section 55
-Paragraph 11
-URI http://asc.fasb.org/extlink&oid=84165509&loc=d3e56451-112766

+ Details

Name:	us-gaap_PlanOfReorganizationDatePlansFiled
Namespace Prefix:	us-gaap_
Data Type:	xbrli:dateItemType
Balance Type:	na
Period Type:	duration

- Definition

Date the plan of reorganization is approved by the bankruptcy court, in CCYY-MM-DD format.

+ References

+ Details

Name:	us-gaap_PlanOfReorganizationDatesPlanConfirmed
Namespace Prefix:	us-gaap_
Data Type:	xbrli:dateItemType
Balance Type:	na
Period Type:	duration

- Definition

Date the plan of reorganization is effective, in CCYY-MM-DD format.

+ References

+ Details

Name:	us-gaap_PlanOfReorganizationDatesPlanIsEffective
Namespace Prefix:	us-gaap_
Data Type:	xbrli:dateItemType
Balance Type:	na
Period Type:	duration

- Definition

Stated as a percentage, the estimated or actual value of the asset at the end of its useful life or when it is no longer serviceable (cannot be used for its original purpose) divided by its [historical] capitalized cost.

+ References

No definition available.

+ Details

Name:	us-gaap_PropertyPlantAndEquipmentSalvageValuePercentage
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Useful life of long lived, physical assets used in the normal conduct of business and not intended for resale, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. Examples include, but not limited to, land, buildings, machinery and equipment, office equipment, furniture and fixtures, and computer equipment.

+ References

No definition available.

+ Details

Name:	us-gaap_PropertyPlantAndEquipmentUsefulLife
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	us-gaap_PropertyPlantAndEquipmentByTypeAxis=us-gaap_MaritimeEquipmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_StatementScenarioAxis=us-gaap_PredecessorMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Interim Financial Statements - Additional Information (Detail)	2 Months Ended	4 Months Ended	6 Months Ended
	Sep. 30, 2017	Jul. 31, 2017	Sep. 30, 2017
Reorganizations [Line Items]
Prepackaged plan of reorganization, date of written order issued by court			Jul. 17, 2017
Prepackaged plan of reorganization, petition date			May 17, 2017
Prepackaged plan of reorganization, date on emerged from bankruptcy			Jul. 31, 2017
Court where petition for bankruptcy was filed			United States Bankruptcy Court for the District of Delaware (the “Bankruptcy Court”)
Planned major maintenance activities, comprehensive surveys to maintain certifications for vessels, consecutive period	5 years
Costs related to recertification of vessels deferred and amortized, period	30 months
Vessels
Reorganizations [Line Items]
Estimated useful lives	20 years
Percentage of salvage values	7.50%		7.50%
Predecessor \| Vessels
Reorganizations [Line Items]
Estimated useful lives		25 years
Percentage of salvage values		10.00%