XML 105 R85.htm IDEA: XBRL DOCUMENT v3.8.0.1

Schedule of Minimum and Maximum Market Value of Plan Assets (Detail)	Dec. 31, 2017
Equity Securities | Minimum
Schedule of Pension and Other Postretirement Plan Assets by Fair Value [Line Items]
Market value objective for plan assets	55.00%
Equity Securities | Maximum
Schedule of Pension and Other Postretirement Plan Assets by Fair Value [Line Items]
Market value objective for plan assets	75.00%
Debt Securities | Minimum
Schedule of Pension and Other Postretirement Plan Assets by Fair Value [Line Items]
Market value objective for plan assets	25.00%
Debt Securities | Maximum
Schedule of Pension and Other Postretirement Plan Assets by Fair Value [Line Items]
Market value objective for plan assets	45.00%
Investment Grade Bonds | Minimum
Schedule of Pension and Other Postretirement Plan Assets by Fair Value [Line Items]
Market value objective for plan assets	0.00%
Investment Grade Bonds | Maximum
Schedule of Pension and Other Postretirement Plan Assets by Fair Value [Line Items]
Market value objective for plan assets	20.00%
Cash and Cash Equivalents | Minimum
Schedule of Pension and Other Postretirement Plan Assets by Fair Value [Line Items]
Market value objective for plan assets	0.00%
Cash and Cash Equivalents | Maximum
Schedule of Pension and Other Postretirement Plan Assets by Fair Value [Line Items]
Market value objective for plan assets	10.00%

X

- Definition

Schedule of Pension and Other Postretirement Plan Assets by Fair Value [Line Items]

+ References

No definition available.

+ Details

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

X

- Definition

Percentage of target investment allocation to total plan assets. Includes, but is not limited to, percentage on weighted-average basis if more than one 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 (d)(5)(i)
-URI http://asc.fasb.org/extlink&oid=82843861&loc=d3e1928-114920

+ Details

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

X

- Details

Name:	us-gaap_InvestmentTypeAxis=us-gaap_EquitySecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_RangeAxis=us-gaap_MinimumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_RangeAxis=us-gaap_MaximumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_InvestmentTypeAxis=us-gaap_DebtSecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_InvestmentTypeAxis=tdw_InvestmentGradeBondsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_InvestmentTypeAxis=us-gaap_CashAndCashEquivalentsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: