| Document And Entity Information - USD ($) | Dec. 31, 2020 | Apr. 12, 2021 | Jun. 30, 2020 |
| Document Information [Line Items] | |||
| Entity, Registrant Name | Tidewater Inc. | ||
| Current Fiscal Year End Date | --12-31 | ||
| Document, Fiscal Period Focus | FY | ||
| Document, Fiscal Year Focus | 2020 | ||
| Document, Type | 10-K/A | ||
| Document, Annual Report | true | ||
| Document, Period End Date | Dec. 31, 2020 | ||
| Document, Transition Report | false | ||
| Entity, File Number | 1-6311 | ||
| Entity, Incorporation, State or Country Code | DE | ||
| Entity, Tax Identification Number | 72-0487776 | ||
| Entity, Address, Address Line One | 6002 Rogerdale Road | ||
| Entity, Address, Address Line Two | Suite 600 | ||
| Entity, Address, City or Town | Houston | ||
| Entity, Address, State or Province | TX | ||
| Entity, Address, Postal Zip Code | 77072 | ||
| City Area Code | 713 | ||
| Local Phone Number | 470-5300 | ||
| Entity, Well-known Seasoned Issuer | No | ||
| Entity, Voluntary Filers | No | ||
| Entity, Current Reporting Status | Yes | ||
| Entity, Interactive Data, Current | Yes | ||
| Entity, Filer Category | Accelerated Filer | ||
| Entity, Small Business | false | ||
| Entity, Emerging Growth Company | false | ||
| Entity, Shell Company | false | ||
| Entity, Public Float | $ 224,000,000 | ||
| Entity, Common Stock Shares, Outstanding | 40,731,777 | ||
| Amendment Description | On March 4, 2021, Tidewater Inc. filed its Annual Report on Form 10-K for the fiscal year ended December 31, 2020 (the “Original Form 10-K”) with the Securities and Exchange Commission (the “SEC”). Tidewater is filing this Amendment No. 1 on Form 10-K/A (the “Form 10-K/A”) because it may not file its definitive proxy statement within 120 days after the end of such fiscal year. Therefore, this Form 10-K/A is being filed to provide the information required in Part III of Form 10-K. | ||
| Amendment Flag | true | ||
| Entity, Central Index Key | 0000098222 | ||
| CommonStock0001ParValuePerShare Custom [Member] | |||
| Document Information [Line Items] | |||
| Title of 12(b) Security | Common Stock, $0.001 par value per share | ||
| Trading Symbol | TDW | ||
| Security Exchange Name | NYSE | ||
| SeriesAWarrantsToPurchaseSharesOfCommonStock Custom [Member] | |||
| Document Information [Line Items] | |||
| Title of 12(b) Security | Series A Warrants to purchase shares of common stock | ||
| Trading Symbol | TDW.WS.A | ||
| Security Exchange Name | NYSE | ||
| SeriesBWarrantsToPurchaseSharesOfCommonStock Custom [Member] | |||
| Document Information [Line Items] | |||
| Title of 12(b) Security | Series B Warrants to purchase shares of common stock | ||
| Trading Symbol | TDW.WS.B | ||
| Security Exchange Name | NYSE | ||
| WarrantsToPurchaseSharesOfCommonStock Custom [Member] | |||
| Document Information [Line Items] | |||
| Title of 12(b) Security | Warrants to purchase shares of common stock | ||
| Trading Symbol | TDW.WS | ||
| Security Exchange Name | NYSEAMER | ||
| PreferredStockPurchaseRights Custom [Member] | |||
| Document Information [Line Items] | |||
| Title of 12(b) Security | Preferred stock purchase rights | ||
| Trading Symbol | N/A | ||
| Security Exchange Name | NYSE |
