Consolidation, Policy [Policy Text Block]

Principles of Consolidation

The consolidated financial statements include the accounts of Tidewater Inc. and its subsidiaries. Intercompany balances and transactions are eliminated in consolidation.

Use of Estimates, Policy [Policy Text Block]

Use of Estimates in Preparation of Financial Statements

The preparation of financial statements in conformity with accounting principles generally accepted in the United States of America requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the consolidated financial statements and the recorded amounts of revenues and expenses during the reporting period. The accompanying consolidated financial statements include estimates for allowance for credit losses, useful lives of property and equipment, income tax provisions, impairments, commitments and contingencies and certain accrued liabilities. We evaluate our estimates and assumptions on an ongoing basis based on a combination of historical information and various other assumptions that are considered reasonable under the particular circumstances, the results of which form the basis for making judgments about carrying values of assets and liabilities that are not readily apparent from other sources. These accounting policies involve judgment and uncertainties to such an extent that there is reasonable likelihood that materially different amounts could have been reported under different conditions or if different assumptions had been used and, as such, actual results may differ from these estimates.

Restricted Cash, Policy [Policy Text Block]

Restricted Cash

We consider cash as restricted when there are contractual agreements that govern the use or withdrawal of the funds.

Property, Plant and Equipment, Policy [Policy Text Block]

Properties and Equipment

Depreciation and Amortization

Upon emergence from Chapter 11 bankruptcy on July 31, 2017, properties and equipment were stated at their fair market values in accordance with fresh-start accounting. Properties and equipment acquired subsequent to fresh start are stated at their acquisition cost. Depreciation is computed primarily on the straight-line basis beginning on acquisition date or on the date construction is completed, with salvage values of 7.5% for marine equipment, using estimated useful lives of 10 - 20 years for marine equipment and 3 - 10 years for other properties and equipment. Depreciation is provided for all vessels unless a vessel meets the criteria to be classified as held for sale. Estimated remaining useful lives are reviewed when there has been a change in circumstances that indicates the original estimated useful life may no longer be appropriate. Upon retirement or disposal of a fixed asset, the costs and related accumulated depreciation are removed from the respective accounts and any gains or losses are included in our consolidated statements of operations.

Maintenance and Repairs

The majority of our vessels require certification inspections twice in every five-year period. These costs include drydocking and survey costs necessary to ensure compliance with applicable regulations and maintain certifications for vessels with classification societies. These certification costs are typically incurred while the vessel is in drydock and may be incurred concurrent with other vessel maintenance and improvement activities. Costs related to the certification of vessels are deferred and amortized over 30 months on a straight-line basis.

Maintenance costs incurred at the time of the recertification drydocking that are not related to the certification of the vessel are expensed as incurred.

Costs related to vessel improvements that either extend the vessel’s useful life or increase the vessel’s functionality are capitalized and depreciated. Vessel modifications that are performed for a specific customer contract are capitalized and amortized over the firm contract term. Major modifications to equipment that are being performed not only for a specific customer contract are capitalized and amortized over the remaining life of the equipment.

Net Properties and Equipment

The following are summaries of net properties and equipment:

	December 31,		December 31,
(In thousands)	2020		2019
Properties and equipment:
Vessels and related equipment	$	940,175	$	1,051,558
Other properties and equipment		16,861		13,119
		957,036		1,064,677
Less accumulated depreciation and amortization		176,718		125,716
Net properties and equipment	$	780,318	$	938,961

As of December 31, 2020, we owned 172 offshore service vessels, including 23 that were reclassified as assets held for sale in current assets. Excluding the 23 vessels held for sale, we owned 149 vessels, 114 of which were actively employed and 35 of which were stacked. As of December 31, 2019, we owned 217 vessels, including 46 that were classified as held for sale and 19 that were stacked. We consider a vessel to be stacked if the vessel crew is disembarked and limited maintenance is being performed. We reduce operating costs by stacking vessels when we do not foresee opportunities to profitably or strategically operate the vessels in the near future. Vessels are stacked when market conditions warrant and they are removed from stack when they are returned to active service, sold or otherwise disposed. We consider our current stacked vessels to be available for return to service. Stacked vessels are considered to be in service and are included in our utilization statistics. Refer to Note (8) for additional discussion of our asset impairments and the reclassification of the vessels held for sale.

Accrued Property And Liability Losses Policy [Policy Text Block]

Accrued Property and Liability Losses

Effective July 1, 2018, we ceased self-insuring claims through our insurance subsidiary. Insurance coverage is now provided by third party insurers. We establish case-based reserves for estimates of reported losses on outstanding claims, estimates received from ceding reinsurers, and reserves based on past experience of unreported losses. Such losses principally relate to our vessel operations and are included as a component of vessel operating costs in the consolidated statements of earnings. The liability for such losses and the related reimbursement receivable from reinsurance companies are classified in the consolidated balance sheets into current and noncurrent amounts based upon estimates of when the liabilities will be settled and when the receivables will be collected.

Income Tax, Policy [Policy Text Block]

Income Taxes

Income taxes are accounted for in accordance with the provisions of ASC 740, Income Taxes. Deferred tax assets and liabilities are recognized for the future tax consequences attributable to differences between the financial statement carrying amounts of existing assets and liabilities and their respective tax bases. Deferred tax assets and liabilities are measured using enacted tax rates expected to apply to taxable income in the years in which those temporary differences are expected to be recovered or settled. The effect on deferred tax assets and liabilities of a change in tax rates is recognized in income in the period that includes the enactment date. Deferred taxes are not provided on undistributed earnings of certain non-U.S. subsidiaries and business ventures because we consider those earnings to be permanently invested abroad.

We record uncertain tax positions on the basis of a two-step process in which (1) we determine whether it is more likely than not that the tax positions would be sustained on the basis of the technical merits of the position and (2) for those tax positions that meet the more-likely-than-not recognition threshold, we recognize the largest amount of tax benefit that was more than 50 percent likely to be realized upon ultimate settlement with the related tax authority. The recognition and measurement of tax liabilities for uncertain tax positions in any tax jurisdiction requires the interpretation of the related tax laws and regulations as well as the use of estimates and assumptions regarding significant future events. Changes in tax laws, regulations, agreements and treaties, foreign currency exchange restrictions or our level of operations or profitability in each taxing jurisdiction could have an impact on the amount of income taxes during any given year.

Cost of Goods and Service [Policy Text Block]

Operating Costs

Vessel operating costs are incurred on a daily basis and consist primarily of costs such as crew wages; repair and maintenance; insurance; fuel, lube oil and supplies; and other vessel expenses, which include costs such as brokers’ commissions, training costs, agent fees, port fees, canal transit fees, temporary importation fees, vessel certification fees, and satellite communication fees. Repair and maintenance costs include both routine costs and major repairs carried out during drydockings, which occur during the economic useful life of the vessel. Vessel operating costs are recognized as incurred on a daily basis.

Earnings Per Share, Policy [Policy Text Block]

Earnings Per Share

We report both basic earnings (loss) per share and diluted earnings (loss) per share. The calculation of basic earnings (loss) per share is computed based on the weighted average number of shares of common stock outstanding. Diluted earnings (loss) per share is computed based on the weighted average number of shares of common stock plus the effect of dilutive potential common shares outstanding during the period using the treasury stock method. Diluted earnings (loss) per share includes the dilutive effect of stock options and restricted stock grants (both time and performance based) awarded as part of our share-based compensation and incentive plans. Per share amounts disclosed in these Notes to Consolidated Financial Statements, unless otherwise indicated, are on a diluted basis.

The components of basic and diluted earnings (loss) per share, are as follows:

	Year Ended December 31,
(In thousands, except share and per share data)	2020			2019			2018
Net loss available to common shareholders	$	(196,242	)	$	(141,743	)	$	(171,517	)
Weighted average outstanding shares of common stock, basic		40,354,638			38,204,934			26,589,883
Dilutive effect of options, warrants and stock awards		—			—			—
Weighted average common stock and equivalents		40,354,638			38,204,934			26,589,883

Loss per share, basic	$	(4.86	)	$	(3.71	)	$	(6.45	)
Loss per share, diluted	$	(4.86	)	$	(3.71	)	$	(6.45	)
Additional information:
Incremental "in-the-money" options, warrants, and restricted stock awards and units outstanding at the end of the period (A)		2,235,310			2,483,956			5,282,574

(A)

For years ended December 31, 2020, 2019 and 2018 we also had 5,923,399 shares of “out-of- the-money” warrants outstanding at the end of each period.

Share-based Payment Arrangement [Policy Text Block]

Stock-Based Compensation

Stock-based compensation transactions are accounted for using a fair-value-based method. We use the Black-Scholes option-pricing model to determine the fair-value of stock-based awards.

Fair Value of Financial Instruments, Policy [Policy Text Block]

Fair Value Measurements

We follow the provisions of ASC 820, for financial assets and liabilities that are measured and reported at fair value on a recurring basis. ASC 820 establishes a hierarchy for inputs used in measuring fair value. Fair value is calculated based on assumptions that market participants would use in pricing assets and liabilities and not on assumptions specific to the entity. The statement requires that each asset and liability carried at fair value be classified into one of the following categories:

Level 1: Quoted market prices in active markets for identical assets or liabilities

Level 2: Observable market-based inputs or unobservable inputs that are corroborated by market data

Level 3: Unobservable inputs that are not corroborated by market data

Our primary financial instruments consist of cash and cash equivalents, restricted cash, trade receivables and trade payables with book values that are considered to be representative of their respective fair values.

Our cash equivalents, which are securities with maturities less than 90 days, are held in money market funds or time deposit accounts with highly rated financial institutions. The carrying value for cash equivalents is considered to be representative of its fair value due to the short duration and conservative nature of the cash equivalent investment portfolio