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Schedule of Fair Value Assets and Liabilities Measured on Recurring Basis (Detail) - USD ($) $ in Thousands | Jun. 30, 2018 | Dec. 31, 2017 | Mar. 31, 2017
--- | --- | --- | ---
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |
Fair value of plan assets |  |  | $ 57,536 |
Total fair value of plan assets | [1] | $ 45 | 8,908 |
Predecessor |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |
Fair value of plan assets |  |  |  | $ 57,146
Total fair value of plan assets |  |  |  | 8,759
Supplemental Executive Retirement Plan |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |
Fair value of plan assets |  |  | 8,909 |
Other pending transactions |  |  | (1) |
Total fair value of plan assets |  | 45 | 8,908 |
Supplemental Executive Retirement Plan | Predecessor |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |
Fair value of plan assets |  |  |  | 8,760
Total fair value of plan assets |  |  |  | 8,760
Pension Plans, Defined Benefit |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |
Fair value of plan assets |  |  | 56,928 |
Accrued income |  |  | 608 |
Total fair value of plan assets |  |  | 57,536 |
Pension Plans, Defined Benefit | Predecessor |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |
Fair value of plan assets |  |  |  | 56,465
Accrued income |  |  |  | 681
Total fair value of plan assets |  |  |  | 57,146
Other | Pension Plans, Defined Benefit |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |
Fair value of plan assets |  |  | 1,404 |
Other | Pension Plans, Defined Benefit | Predecessor |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |
Fair value of plan assets |  |  |  | 1,298
Measured At Net Asset Value | Supplemental Executive Retirement Plan |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |
Fair value of plan assets |  |  | 1,725 |
Total fair value of plan assets |  | 45 | 1,725 |
Measured At Net Asset Value | Supplemental Executive Retirement Plan | Predecessor |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |
Fair value of plan assets |  |  |  | 1,720
Total fair value of plan assets |  |  |  | 1,720
Cash and Cash Equivalents | Supplemental Executive Retirement Plan |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |
Fair value of plan assets |  | 45 | 246 |
Cash and Cash Equivalents | Supplemental Executive Retirement Plan | Predecessor |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |
Fair value of plan assets |  |  |  | 323
Cash and Cash Equivalents | Pension Plans, Defined Benefit |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |
Fair value of plan assets |  |  | 834 |
Cash and Cash Equivalents | Pension Plans, Defined Benefit | Predecessor |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |
Fair value of plan assets |  |  |  | 989
Cash and Cash Equivalents | Measured At Net Asset Value | Supplemental Executive Retirement Plan |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |
Fair value of plan assets |  | $ 45 | 49 |
Cash and Cash Equivalents | Measured At Net Asset Value | Supplemental Executive Retirement Plan | Predecessor |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |
Fair value of plan assets |  |  |  | 72
Equity Securities | Supplemental Executive Retirement Plan |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |
Fair value of plan assets |  |  | 5,295 |
Debt Securities | Supplemental Executive Retirement Plan |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |
Fair value of plan assets |  |  | 3,368 |
Debt Securities | Measured At Net Asset Value | Supplemental Executive Retirement Plan |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |
Fair value of plan assets |  |  | 1,676 |
US Government Agencies Debt Securities | Supplemental Executive Retirement Plan |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |
Fair value of plan assets |  |  | 1,692 |
US Government Agencies Debt Securities | Supplemental Executive Retirement Plan | Predecessor |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |
Fair value of plan assets |  |  |  | 1,613
US Government Agencies Debt Securities | Pension Plans, Defined Benefit |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |
Fair value of plan assets |  |  | 4,238 |
US Government Agencies Debt Securities | Pension Plans, Defined Benefit | Predecessor |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |
Fair value of plan assets |  |  |  | 3,770
Collateralized mortgage securities | Pension Plans, Defined Benefit |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |
Fair value of plan assets |  |  | 1,032 |
Collateralized mortgage securities | Pension Plans, Defined Benefit | Predecessor |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |
Fair value of plan assets |  |  |  | 2,537
Corporate Debt Securities | Pension Plans, Defined Benefit |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |
Fair value of plan assets |  |  | 49,420 |
Corporate Debt Securities | Pension Plans, Defined Benefit | Predecessor |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |
Fair value of plan assets |  |  |  | 47,871
Common stock | Supplemental Executive Retirement Plan |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |
Fair value of plan assets |  |  | 3,599 |
Common stock | Supplemental Executive Retirement Plan | Predecessor |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |
Fair value of plan assets |  |  |  | 3,561
Foreign Stock | Supplemental Executive Retirement Plan |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |
Fair value of plan assets |  |  | 183 |
Foreign Stock | Supplemental Executive Retirement Plan | Predecessor |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |
Fair value of plan assets |  |  |  | 132
American Depository Receipts | Supplemental Executive Retirement Plan |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |
Fair value of plan assets |  |  | 1,429 |
American Depository Receipts | Supplemental Executive Retirement Plan | Predecessor |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |
Fair value of plan assets |  |  |  | 1,387
Preferred American Depository Receipts | Supplemental Executive Retirement Plan |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |
Fair value of plan assets |  |  | 12 |
Preferred American Depository Receipts | Supplemental Executive Retirement Plan | Predecessor |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |
Fair value of plan assets |  |  |  | 20
Real Estate Investment Trusts | Supplemental Executive Retirement Plan |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |
Fair value of plan assets |  |  | 72 |
Real Estate Investment Trusts | Supplemental Executive Retirement Plan | Predecessor |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |
Fair value of plan assets |  |  |  | 76
Open Ended Mutual Funds | Supplemental Executive Retirement Plan |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |
Fair value of plan assets |  |  | 1,676 |
Open Ended Mutual Funds | Supplemental Executive Retirement Plan | Predecessor |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |
Fair value of plan assets |  |  |  | 1,648
Open Ended Mutual Funds | Measured At Net Asset Value | Supplemental Executive Retirement Plan |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |
Fair value of plan assets |  |  | 1,676 |
Open Ended Mutual Funds | Measured At Net Asset Value | Supplemental Executive Retirement Plan | Predecessor |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |
Fair value of plan assets |  |  |  | 1,648
Quoted Prices In Active Markets (Level 1) | Supplemental Executive Retirement Plan |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |
Fair value of plan assets |  |  | 6,173 |
Other pending transactions |  |  | (1) |
Total fair value of plan assets |  |  | 6,172 |
Quoted Prices In Active Markets (Level 1) | Supplemental Executive Retirement Plan | Predecessor |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |
Fair value of plan assets |  |  |  | 6,023
Total fair value of plan assets |  |  |  | 6,023
Quoted Prices In Active Markets (Level 1) | Pension Plans, Defined Benefit |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |
Fair value of plan assets |  |  | 4,629 |
Accrued income |  |  | 608 |
Total fair value of plan assets |  |  | 5,237 |
Quoted Prices In Active Markets (Level 1) | Pension Plans, Defined Benefit | Predecessor |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |
Fair value of plan assets |  |  |  | 4,215
Accrued income |  |  |  | 681
Total fair value of plan assets |  |  |  | 4,896
Quoted Prices In Active Markets (Level 1) | Other | Pension Plans, Defined Benefit |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |
Fair value of plan assets |  |  | 172 |
Quoted Prices In Active Markets (Level 1) | Other | Pension Plans, Defined Benefit | Predecessor |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |
Fair value of plan assets |  |  |  | 100
Quoted Prices In Active Markets (Level 1) | Cash and Cash Equivalents | Supplemental Executive Retirement Plan |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |
Fair value of plan assets |  |  | 27 |
Quoted Prices In Active Markets (Level 1) | Cash and Cash Equivalents | Supplemental Executive Retirement Plan | Predecessor |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |
Fair value of plan assets |  |  |  | 15
Quoted Prices In Active Markets (Level 1) | Cash and Cash Equivalents | Pension Plans, Defined Benefit |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |
Fair value of plan assets |  |  | 219 |
Quoted Prices In Active Markets (Level 1) | Cash and Cash Equivalents | Pension Plans, Defined Benefit | Predecessor |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |
Fair value of plan assets |  |  |  | 345
Quoted Prices In Active Markets (Level 1) | Equity Securities | Supplemental Executive Retirement Plan |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |
Fair value of plan assets |  |  | 5,295 |
Quoted Prices In Active Markets (Level 1) | Debt Securities | Supplemental Executive Retirement Plan |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |
Fair value of plan assets |  |  | 851 |
Quoted Prices In Active Markets (Level 1) | US Government Agencies Debt Securities | Supplemental Executive Retirement Plan |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |
Fair value of plan assets |  |  | 851 |
Quoted Prices In Active Markets (Level 1) | US Government Agencies Debt Securities | Supplemental Executive Retirement Plan | Predecessor |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |
Fair value of plan assets |  |  |  | 832
Quoted Prices In Active Markets (Level 1) | US Government Agencies Debt Securities | Pension Plans, Defined Benefit |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |
Fair value of plan assets |  |  | 4,238 |
Quoted Prices In Active Markets (Level 1) | US Government Agencies Debt Securities | Pension Plans, Defined Benefit | Predecessor |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |
Fair value of plan assets |  |  |  | 3,770
Quoted Prices In Active Markets (Level 1) | Common stock | Supplemental Executive Retirement Plan |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |
Fair value of plan assets |  |  | 3,599 |
Quoted Prices In Active Markets (Level 1) | Common stock | Supplemental Executive Retirement Plan | Predecessor |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |
Fair value of plan assets |  |  |  | 3,561
Quoted Prices In Active Markets (Level 1) | Foreign Stock | Supplemental Executive Retirement Plan |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |
Fair value of plan assets |  |  | 183 |
Quoted Prices In Active Markets (Level 1) | Foreign Stock | Supplemental Executive Retirement Plan | Predecessor |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |
Fair value of plan assets |  |  |  | 132
Quoted Prices In Active Markets (Level 1) | American Depository Receipts | Supplemental Executive Retirement Plan |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |
Fair value of plan assets |  |  | 1,429 |
Quoted Prices In Active Markets (Level 1) | American Depository Receipts | Supplemental Executive Retirement Plan | Predecessor |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |
Fair value of plan assets |  |  |  | 1,387
Quoted Prices In Active Markets (Level 1) | Preferred American Depository Receipts | Supplemental Executive Retirement Plan |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |
Fair value of plan assets |  |  | 12 |
Quoted Prices In Active Markets (Level 1) | Preferred American Depository Receipts | Supplemental Executive Retirement Plan | Predecessor |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |
Fair value of plan assets |  |  |  | 20
Quoted Prices In Active Markets (Level 1) | Real Estate Investment Trusts | Supplemental Executive Retirement Plan |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |
Fair value of plan assets |  |  | 72 |
Quoted Prices In Active Markets (Level 1) | Real Estate Investment Trusts | Supplemental Executive Retirement Plan | Predecessor |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |
Fair value of plan assets |  |  |  | 76
Level 2 | Supplemental Executive Retirement Plan |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |
Fair value of plan assets |  |  | 1,011 |
Total fair value of plan assets |  |  | 1,011 |
Level 2 | Supplemental Executive Retirement Plan | Predecessor |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |
Fair value of plan assets |  |  |  | 1,017
Total fair value of plan assets |  |  |  | 1,017
Level 2 | Pension Plans, Defined Benefit |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |
Fair value of plan assets |  |  | 52,299 |
Total fair value of plan assets |  |  | 52,299 |
Level 2 | Pension Plans, Defined Benefit | Predecessor |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |
Fair value of plan assets |  |  |  | 52,250
Total fair value of plan assets |  |  |  | 52,250
Level 2 | Other | Pension Plans, Defined Benefit |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |
Fair value of plan assets |  |  | 1,232 |
Level 2 | Other | Pension Plans, Defined Benefit | Predecessor |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |
Fair value of plan assets |  |  |  | 1,198
Level 2 | Cash and Cash Equivalents | Supplemental Executive Retirement Plan |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |
Fair value of plan assets |  |  | 170 |
Level 2 | Cash and Cash Equivalents | Supplemental Executive Retirement Plan | Predecessor |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |
Fair value of plan assets |  |  |  | 236
Level 2 | Cash and Cash Equivalents | Pension Plans, Defined Benefit |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |
Fair value of plan assets |  |  | 615 |
Level 2 | Cash and Cash Equivalents | Pension Plans, Defined Benefit | Predecessor |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |
Fair value of plan assets |  |  |  | 644
Level 2 | Debt Securities | Supplemental Executive Retirement Plan |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |
Fair value of plan assets |  |  | 841 |
Level 2 | US Government Agencies Debt Securities | Supplemental Executive Retirement Plan |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |
Fair value of plan assets |  |  | 841 |
Level 2 | US Government Agencies Debt Securities | Supplemental Executive Retirement Plan | Predecessor |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |
Fair value of plan assets |  |  |  | 781
Level 2 | Collateralized mortgage securities | Pension Plans, Defined Benefit |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |
Fair value of plan assets |  |  | 1,032 |
Level 2 | Collateralized mortgage securities | Pension Plans, Defined Benefit | Predecessor |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |
Fair value of plan assets |  |  |  | 2,537
Level 2 | Corporate Debt Securities | Pension Plans, Defined Benefit |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |
Fair value of plan assets |  |  | $ 49,420 |
Level 2 | Corporate Debt Securities | Pension Plans, Defined Benefit | Predecessor |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |
Fair value of plan assets |  |  |  | $ 47,871
[1] | Tidewater converted substantially all investments held in the rabbi trust to cash to fund a lump sum benefit to the former CEO in May 2018. Refer to Note (6) for more information regarding this payment.

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