Document and Entity Information - USD ($)	12 Months Ended
	Dec. 31, 2019	Feb. 18, 2020	Jun. 30, 2019
Document Information [Line Items]
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2019
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	FY
Entity Registrant Name	Tidewater Inc.
Entity Central Index Key	0000098222
Entity Well-known Seasoned Issuer	Yes
Entity Current Reporting Status	Yes
Current Fiscal Year End Date	--12-31
Entity Voluntary Filers	No
Entity Filer Category	Large Accelerated Filer
Entity Shell Company	false
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Common Stock, Shares Outstanding		40,111,245
Entity Public Float			$ 883,454,841
Entity Interactive Data Current	Yes
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 Line2	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
Document Annual Report	true
Document Transition Report	false
Documents Incorporated by Reference	None.
Common Stock
Document Information [Line Items]
Trading Symbol	TDW
Title of 12(b) Security	Common Stock, $0.001 par value per share
Security Exchange Name	NYSE
Series A Warrants
Document Information [Line Items]
Trading Symbol	TDW.WS.A
Title of 12(b) Security	Series A Warrants to purchase shares of common stock
Security Exchange Name	NYSE
Series B Warrants
Document Information [Line Items]
Trading Symbol	TDW.WS.B
Title of 12(b) Security	Series B Warrants to purchase shares of common stock
Security Exchange Name	NYSE
Warrants to Purchase common stock
Document Information [Line Items]
Trading Symbol	TDW.WS
Title of 12(b) Security	Warrants to purchase shares of common stock
Security Exchange Name	NYSEAMER