CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE LOSS (Unaudited) (Parenthetical) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
Jun. 30, 2020	Jun. 30, 2019
Statement Of Income And Comprehensive Income [Abstract]
Change in pension plan and supplemental pension plan liability	$ 0.2	$ 0.2

Other comprehensive income pension plan and supplemental pension plan liability adjustment tax period increase decrease.

No definition available.

Name:	tdw_OtherComprehensiveIncomePensionPlanAndSupplementalPensionPlanLiabilityAdjustmentTaxPeriodIncreaseDecrease
Namespace Prefix:	tdw_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration