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Number of Tidewater Common Stock Shares, Series A Warrants and Series B Warrants Held by Plan (Detail) - shares | Dec. 31, 2018 | Dec. 31, 2017 | Jul. 31, 2017 | Mar. 31, 2017
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Defined Contribution Plan Disclosure [Line Items] |  |  |  |
Number of shares of Tidewater common stock held by 401(k) plan | 7,075 |  |  |
Warrants issued | 2,547 | 924,125 |  |
Defined Contribution Savings Plan 401k |  |  |  |
Defined Contribution Plan Disclosure [Line Items] |  |  |  |
Number of shares of Tidewater common stock held by 401(k) plan |  | 8,074 |  |
Defined Contribution Savings Plan 401k | Predecessor |  |  |  |
Defined Contribution Plan Disclosure [Line Items] |  |  |  |
Number of shares of Tidewater common stock held by 401(k) plan |  |  | 264,504 | 291,957
Defined Contribution Savings Plan 401k | Series A Warrants |  |  |  |
Defined Contribution Plan Disclosure [Line Items] |  |  |  |
Warrants issued |  | 9,030 |  |
Defined Contribution Savings Plan 401k | Series B |  |  |  |
Defined Contribution Plan Disclosure [Line Items] |  |  |  |
Warrants issued |  | 9,762 |  |

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- Definition Number of securities into which the class of warrant or right may be converted. For example, but not limited to, 500,000 warrants may be converted into 1,000,000 shares. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 235 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.4-08.(i)(2)) -URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690 + Details
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- Definition Number of common stock held in a trust that has been set up specifically to accumulate stock for the sole purpose of distribution to participating employees but not yet earned. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 40 -Section 25 -Paragraph 12 -URI http://asc.fasb.org/extlink&oid=109244457&loc=d3e16701-113920 + Details
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