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Change in Plan Assets and Obligations (Detail) - USD ($) $ in Thousands | 4 Months Ended | 5 Months Ended | 9 Months Ended | 12 Months Ended
--- | --- | --- | --- | ---
Jul. 31, 2017 | Dec. 31, 2017 | Dec. 31, 2017 | Mar. 31, 2017 | Mar. 31, 2016
Schedule Of Pension And Other Postretirement Benefits Changes In Benefit Obligation And Fair Value Of Plan Assets [Line Items] |  |  |  |  |
Benefit obligation at end of the period |  | $ 103,443 | $ 103,443 |  |
Predecessor |  |  |  |  |
Schedule Of Pension And Other Postretirement Benefits Changes In Benefit Obligation And Fair Value Of Plan Assets [Line Items] |  |  |  |  |
Benefit obligation at beginning of the period | $ 97,941 |  | 97,941 |  |
Benefit obligation at end of the period |  |  |  | $ 97,941 |
Pension Plans, Defined Benefit |  |  |  |  |
Schedule Of Pension And Other Postretirement Benefits Changes In Benefit Obligation And Fair Value Of Plan Assets [Line Items] |  |  |  |  |
Employer contributions |  |  | 0 | 3,000 | $ 0
Current liabilities |  | (10,731) | (10,731) |  |
Noncurrent liabilities |  | (35,252) | (35,252) |  |
Net amount recognized |  | (45,983) | (45,983) |  |
Pension Plans, Defined Benefit | Predecessor |  |  |  |  |
Schedule Of Pension And Other Postretirement Benefits Changes In Benefit Obligation And Fair Value Of Plan Assets [Line Items] |  |  |  |  |
Actuarial (gain) loss | 748 |  |  | 1,785 |
Current liabilities | (1,791) |  |  | (1,791) |
Noncurrent liabilities | (41,642) |  |  | (39,087) |
Net amount recognized | (43,433) |  |  | (40,878) |
Pension Plans, Defined Benefit | Change in Benefit Obligations |  |  |  |  |
Schedule Of Pension And Other Postretirement Benefits Changes In Benefit Obligation And Fair Value Of Plan Assets [Line Items] |  |  |  |  |
Benefit obligation at beginning of the period |  | 101,490 |  |  |
Service cost |  | 546 |  |  |
Interest cost |  | 1,599 |  |  |
Plan curtailment |  | (432) |  |  |
Benefits paid |  | (2,059) |  |  |
Actuarial (gain) loss |  | 2,322 |  |  |
Foreign currency exchange rate changes |  | (23) |  |  |
Benefit obligation at end of the period | 101,490 | 103,443 | 103,443 |  |
Pension Plans, Defined Benefit | Change in Benefit Obligations | Predecessor |  |  |  |  |
Schedule Of Pension And Other Postretirement Benefits Changes In Benefit Obligation And Fair Value Of Plan Assets [Line Items] |  |  |  |  |
Benefit obligation at beginning of the period | 97,941 | 101,490 | 97,941 | 95,830 |
Service cost | 393 |  |  | 1,182 |
Interest cost | 1,313 |  |  | 3,814 |
Benefits paid | (1,610) |  |  | (4,895) |
Actuarial (gain) loss | 3,322 |  |  | 2,082 |
Foreign currency exchange rate changes | 131 |  |  | (72) |
Benefit obligation at end of the period | 101,490 |  |  | 97,941 | 95,830
Pension Plans, Defined Benefit | Change In Plan Assets |  |  |  |  |
Schedule Of Pension And Other Postretirement Benefits Changes In Benefit Obligation And Fair Value Of Plan Assets [Line Items] |  |  |  |  |
Fair value of plan assets at beginning of the period |  | 58,148 |  |  |
Actual return |  | 1,182 |  |  |
Expected return |  | 32 |  |  |
Actuarial (gain) loss |  | 217 |  |  |
Administrative expenses |  | (15) |  |  |
Plan curtailment |  | (100) |  |  |
Employer contributions |  | 625 |  |  |
Benefits paid |  | (2,059) |  |  |
Foreign currency exchange rate changes |  | (60) |  |  |
Fair value of plan assets at end of the period | 58,148 | 57,536 | 57,536 |  |
Payroll tax unrecognized in benefit obligation at end of the period |  | 76 | 76 |  |
Unfunded status at end of the period |  | (45,983) | (45,983) |  |
Pension Plans, Defined Benefit | Change In Plan Assets | Predecessor |  |  |  |  |
Schedule Of Pension And Other Postretirement Benefits Changes In Benefit Obligation And Fair Value Of Plan Assets [Line Items] |  |  |  |  |
Fair value of plan assets at beginning of the period | 57,146 | 58,148 | 57,146 | 57,174 |
Actual return | 2,138 |  |  | 577 |
Expected return | 16 |  |  | 51 |
Actuarial (gain) loss | 109 |  |  | 148 |
Administrative expenses | (7) |  |  | (27) |
Employer contributions | 435 |  |  | 4,465 |
Benefits paid | (1,610) |  |  | (4,895) |
Foreign currency exchange rate changes | 139 |  |  | (51) |
Fair value of plan assets at end of the period | 58,148 |  |  | 57,146 | 57,174
Payroll tax unrecognized in benefit obligation at end of the period | 91 |  |  | 83 |
Unfunded status at end of the period | (43,433) |  |  | (40,878) |
Other Pension Plans, Defined Benefit |  |  |  |  |
Schedule Of Pension And Other Postretirement Benefits Changes In Benefit Obligation And Fair Value Of Plan Assets [Line Items] |  |  |  |  |
Current liabilities |  | (282) | (282) |  |
Noncurrent liabilities |  | (2,642) | (2,642) |  |
Net amount recognized |  | (2,924) | (2,924) |  |
Other Pension Plans, Defined Benefit | Predecessor |  |  |  |  |
Schedule Of Pension And Other Postretirement Benefits Changes In Benefit Obligation And Fair Value Of Plan Assets [Line Items] |  |  |  |  |
Actuarial (gain) loss | (335) |  |  | (1,138) |
Current liabilities | (418) |  |  | (418) |
Noncurrent liabilities | (4,399) |  |  | (4,393) |
Net amount recognized | (4,817) |  |  | (4,811) |
Other Pension Plans, Defined Benefit | Change in Benefit Obligations |  |  |  |  |
Schedule Of Pension And Other Postretirement Benefits Changes In Benefit Obligation And Fair Value Of Plan Assets [Line Items] |  |  |  |  |
Benefit obligation at beginning of the period |  | 4,817 |  |  |
Service cost |  | 29 |  |  |
Interest cost |  | 75 |  |  |
Participant contributions |  | 65 |  |  |
Plan amendment |  | (1,861) |  |  |
Benefits paid |  | (526) |  |  |
Actuarial (gain) loss |  | 325 |  |  |
Benefit obligation at end of the period | 4,817 | 2,924 | 2,924 |  |
Other Pension Plans, Defined Benefit | Change in Benefit Obligations | Predecessor |  |  |  |  |
Schedule Of Pension And Other Postretirement Benefits Changes In Benefit Obligation And Fair Value Of Plan Assets [Line Items] |  |  |  |  |
Benefit obligation at beginning of the period | 4,811 | 4,817 | 4,811 | 5,573 |
Service cost | 23 |  |  | 81 |
Interest cost | 64 |  |  | 201 |
Participant contributions | 58 |  |  | 411 |
Benefits paid | (346) |  |  | (1,170) |
Actuarial (gain) loss | 207 |  |  | (285) |
Benefit obligation at end of the period | 4,817 |  |  | 4,811 | $ 5,573
Other Pension Plans, Defined Benefit | Change In Plan Assets |  |  |  |  |
Schedule Of Pension And Other Postretirement Benefits Changes In Benefit Obligation And Fair Value Of Plan Assets [Line Items] |  |  |  |  |
Employer contributions |  | 461 |  |  |
Participant contributions |  | 65 |  |  |
Benefits paid |  | (526) |  |  |
Unfunded status at end of the period |  | $ (2,924) | $ (2,924) |  |
Other Pension Plans, Defined Benefit | Change In Plan Assets | Predecessor |  |  |  |  |
Schedule Of Pension And Other Postretirement Benefits Changes In Benefit Obligation And Fair Value Of Plan Assets [Line Items] |  |  |  |  |
Employer contributions | 288 |  |  | 759 |
Participant contributions | 58 |  |  | 411 |
Benefits paid | (346) |  |  | (1,170) |
Unfunded status at end of the period | $ (4,817) |  |  | $ (4,811) |

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