XML 108 R99.htm IDEA: XBRL DOCUMENT
v3.10.0.1

Assumed Health Care Cost Trend Rates (Detail) - Pre Sixty Five Coverage | 12 Months Ended
--- | ---
Dec. 31, 2017
Schedule of Pension Expected Future Benefit Payments [Line Items] |
Accumulated postretirement benefit obligation | 7.60%
Net periodic postretirement benefit obligation | 7.60%
Ultimate health care cost trend | 4.54%
Ultimate year health care cost trend rate is achieved | 2038
Net periodic postretirement benefit obligation December 31, 2018 | 7.45%

X
- Definition Defined Benefit Plan Assumed Health Care Cost Trend Net Periodic Postretirement Benefit Cost + References No definition available. + Details
Name: | tdw_DefinedBenefitPlanAssumedHealthCareCostTrendNetPeriodicPostretirementBenefitCost
Namespace Prefix: | tdw_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Defined Benefit Plan Assumed Health Care Cost Trend Postretirement Benefit Obligation + References No definition available. + Details
Name: | tdw_DefinedBenefitPlanAssumedHealthCareCostTrendPostretirementBenefitObligation
Namespace Prefix: | tdw_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Defined Benefit Plan, Ultimate Health Care Cost Trend Rate, Postretirement Benefit Obligation + References No definition available. + Details
Name: | tdw_DefinedBenefitPlanUltimateHealthCareCostTrendRatePostretirementBenefitObligation
Namespace Prefix: | tdw_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Defined Benefit Plan Year That Rate Reaches Ultimate Trend Rate Postretirement Benefit Obligation + References No definition available. + Details
Name: | tdw_DefinedBenefitPlanYearThatRateReachesUltimateTrendRatePostretirementBenefitObligation
Namespace Prefix: | tdw_
Data Type: | xbrli:gYearItemType
Balance Type: | na
Period Type: | duration

X
- Definition Schedule Of Pension Expected Future Benefit Payments [Line Items] + References No definition available. + Details
Name: | tdw_ScheduleOfPensionExpectedFutureBenefitPaymentsLineItems
Namespace Prefix: | tdw_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Assumed rate, for next fiscal year, based on annual change in cost of health care cost benefits used to measure expected cost of benefits covered by defined benefit postretirement plan. Factors include, but are not limited to, estimate of health care inflation, change in health care utilization or delivery pattern, technological advances, and change in health status of participant. Excludes factors for change in composition of plan population by age and dependency status. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (l) -URI http://asc.fasb.org/extlink&oid=108410482&loc=d3e1928-114920 + Details
Name: | us-gaap_DefinedBenefitPlanHealthCareCostTrendRateAssumedNextFiscalYear
Namespace Prefix: | us-gaap_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Details
Name: | us-gaap_RetirementPlanNameAxis=tdw_PreSixtyFiveCoverageMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |