XML 67 R55.htm IDEA: XBRL DOCUMENT
v3.8.0.1

Schedule of Net Periodic Benefit Cost (Detail) - USD ($) $ in Thousands | 1 Months Ended | 2 Months Ended | 3 Months Ended | 4 Months Ended | 6 Months Ended
--- | --- | --- | --- | --- | ---
Jul. 31, 2017 | Sep. 30, 2017 | Sep. 30, 2016 | Jul. 31, 2017 | Sep. 30, 2016
Pension Benefits |  |  |  |  |
Net Period Benefit Cost Assumptions [Line Items] |  |  |  |  |
Service cost |  | $ 203 |  |  |
Interest cost |  | 624 |  |  |
Expected return on plan assets |  | (332) |  |  |
Administrative expenses |  | 2 |  |  |
Net periodic benefit cost |  | 497 |  |  |
Pension Benefits | Predecessor |  |  |  |  |
Net Period Benefit Cost Assumptions [Line Items] |  |  |  |  |
Service cost | $ 99 |  | $ 254 | $ 393 | $ 506
Interest cost | 328 |  | 941 | 1,313 | 1,882
Expected return on plan assets | (173) |  | (548) | (691) | (1,097)
Administrative expenses | 1 |  | 2 | 3 | 4
Recognized actuarial (benefit) loss | 187 |  | 446 | 748 | 892
Net periodic benefit cost | 442 |  | 1,095 | 1,766 | 2,187
Other Benefits |  |  |  |  |
Net Period Benefit Cost Assumptions [Line Items] |  |  |  |  |
Service cost |  | 12 |  |  |
Interest cost |  | 30 |  |  |
Net periodic benefit cost |  | $ 42 |  |  |
Other Benefits | Predecessor |  |  |  |  |
Net Period Benefit Cost Assumptions [Line Items] |  |  |  |  |
Service cost | 6 |  | 20 | 23 | 40
Interest cost | 16 |  | 50 | 64 | 100
Amortization of prior service cost | (232) |  | (1,086) | (927) | (2,172)
Recognized actuarial (benefit) loss | (83) |  | (285) | (335) | (570)
Net periodic benefit cost | $ (293) |  | $ (1,301) | $ (1,175) | $ (2,602)

X
- Definition Net Period Benefit Cost Assumptions [Line Items] + References No definition available. + Details
Name: | tdw_NetPeriodBenefitCostAssumptionsLineItems
Namespace Prefix: | tdw_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount of gain (loss) from change in actuarial assumptions which (increases) decreases benefit obligation of defined benefit plan. Assumptions include, but are not limited to, interest, mortality, employee turnover, salary, and temporary deviation from substantive plan. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (a)(4) -URI http://asc.fasb.org/extlink&oid=82843861&loc=d3e1928-114920 + Details
Name: | us-gaap_DefinedBenefitPlanActuarialGainLoss
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Amount of administration expense of defined benefit plan which decreases plan assets. Excludes plan administration expense paid by employer. + References No definition available. + Details
Name: | us-gaap_DefinedBenefitPlanAdministrationExpenses
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Amount of prior service cost (credit) recognized in net periodic benefit cost (credit) of defined benefit plan. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (h)(5) -URI http://asc.fasb.org/extlink&oid=82843861&loc=d3e1928-114920 + Details
Name: | us-gaap_DefinedBenefitPlanAmortizationOfPriorServiceCostCredit
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Amount of expected return (loss) recognized in net periodic benefit (cost) credit, calculated based on expected long-term rate of return and market-related value of plan assets of defined benefit plan. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (h)(3) -URI http://asc.fasb.org/extlink&oid=82843861&loc=d3e1928-114920 + Details
Name: | us-gaap_DefinedBenefitPlanExpectedReturnOnPlanAssets
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Amount of cost recognized for passage of time related to defined benefit plan. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (h)(2) -URI http://asc.fasb.org/extlink&oid=82843861&loc=d3e1928-114920 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (a)(2) -URI http://asc.fasb.org/extlink&oid=82843861&loc=d3e1928-114920 + Details
Name: | us-gaap_DefinedBenefitPlanInterestCost
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Amount of net periodic benefit cost (credit) for defined benefit plan. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (h) -URI http://asc.fasb.org/extlink&oid=82843861&loc=d3e1928-114920 + Details
Name: | us-gaap_DefinedBenefitPlanNetPeriodicBenefitCost
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Amount of cost for actuarial present value of benefits attributed to service rendered by employee for defined benefit plan. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (h)(1) -URI http://asc.fasb.org/extlink&oid=82843861&loc=d3e1928-114920 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (a)(1) -URI http://asc.fasb.org/extlink&oid=82843861&loc=d3e1928-114920 + Details
Name: | us-gaap_DefinedBenefitPlanServiceCost
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

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

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

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