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Change in Plan Assets and Obligations (Detail) - USD ($) | 4 Months Ended | 5 Months Ended | 9 Months Ended | 12 Months Ended
--- | --- | --- | --- | ---
Jul. 31, 2017 | Dec. 31, 2017 | Dec. 31, 2017 | Dec. 31, 2018 | Mar. 31, 2017
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 |  |  |  |  | $ 90,247,000 |
Fair value of plan assets at end of the period |  |  |  |  | 56,790,000 |
Predecessor |  |  |  |  |  |
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 |  |  | $ 103,443,000 | $ 103,443,000 |  |
Fair value of plan assets at end of the period |  |  | 57,536,000 | 57,536,000 |  |
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 | 0 | $ 3,000,000
Fair value of plan assets at end of the period |  |  | 56,928,000 | 56,928,000 | 56,209,000 |
Current liabilities |  |  | (10,731,000) | (10,731,000) | (1,380,000) |
Noncurrent liabilities |  |  | (35,252,000) | (35,252,000) | (32,161,000) |
Net amount recognized |  |  | (45,983,000) | (45,983,000) | (33,541,000) |
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] |  |  |  |  |  |
Increase in benefit obligation and plan assets due to business combination |  |  |  |  | 5,463,000 |
Actuarial (gain) loss |  |  | (217,000) |  | (275,000) |
Settlement |  |  |  |  | (8,885,000) |
Fair value of plan assets at beginning of the period |  |  | 58,148,000 |  | 57,536,000 |
Actual return |  |  | 1,182,000 |  | (2,128,000) |
Expected return |  |  | 32,000 |  | 112,000 |
Administrative expenses |  |  | (15,000) |  | (36,000) |
Plan curtailment |  |  | (100,000) |  |  |
Employer contributions |  |  | 625,000 |  | 10,546,000 |
Benefits paid |  |  | (2,059,000) |  | (5,467,000) |
Foreign currency exchange rate changes |  |  | (60,000) |  | (76,000) |
Fair value of plan assets at end of the period |  |  | 57,536,000 | 57,536,000 | 56,790,000 |
Payroll tax unrecognized in benefit obligation at end of the period |  |  | 76,000 | 76,000 | 84,000 |
Unfunded status at end of the period |  |  | (45,983,000) |  | (33,541,000) |
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 |  | $ 748,000 |  |  |  | 1,785,000
Current liabilities |  | (1,791,000) |  |  |  | (1,791,000)
Noncurrent liabilities |  | (41,642,000) |  |  |  | (39,087,000)
Net amount recognized |  | (43,433,000) |  |  |  | (40,878,000)
Pension Plans, Defined Benefit | Predecessor | Change In Plan Assets |  |  |  |  |  |
Schedule of Pension and Other Postretirement Benefits Changes in Benefit Obligation and Fair Value of Plan Assets [Line Items] |  |  |  |  |  |
Actuarial (gain) loss |  | (109,000) |  |  |  | (148,000)
Fair value of plan assets at beginning of the period |  | 57,146,000 |  | 57,146,000 |  | 57,174,000
Actual return |  | 2,138,000 |  |  |  | 577,000
Expected return |  | 16,000 |  |  |  | 51,000
Administrative expenses |  | (7,000) |  |  |  | (27,000)
Employer contributions |  | 435,000 |  |  |  | 4,465,000
Benefits paid |  | (1,610,000) |  |  |  | (4,895,000)
Foreign currency exchange rate changes |  | 139,000 |  |  |  | (51,000)
Fair value of plan assets at end of the period |  | 58,148,000 |  |  |  | 57,146,000
Payroll tax unrecognized in benefit obligation at end of the period |  | 91,000 |  |  |  | 83,000
Unfunded status at end of the period |  | (43,433,000) |  |  |  | (40,878,000)
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 |  |  | 101,490,000 |  | 103,443,000 |
Increase in benefit obligation and plan assets due to business combination |  |  |  |  | 5,474,000 |
Service cost |  |  | 546,000 |  | 294,000 |
Interest cost |  |  | 1,599,000 |  | 3,605,000 |
Plan curtailment |  |  | (432,000) |  |  |
Benefits paid |  |  | (2,059,000) |  | (5,467,000) |
Actuarial (gain) loss | [1] |  | 2,322,000 |  | (8,105,000) |
Settlement |  |  |  |  | (8,885,000) |
Foreign currency exchange rate changes |  |  | (23,000) |  | (112,000) |
Benefit obligation at end of the period |  |  | 103,443,000 | 103,443,000 | 90,247,000 |
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 |  | 97,941,000 |  | 97,941,000 |  | 95,830,000
Service cost |  | 393,000 |  |  |  | 1,182,000
Interest cost |  | 1,313,000 |  |  |  | 3,814,000
Benefits paid |  | (1,610,000) |  |  |  | (4,895,000)
Actuarial (gain) loss | [1] | 3,322,000 |  |  |  | 2,082,000
Foreign currency exchange rate changes |  | 131,000 |  |  |  | (72,000)
Benefit obligation at end of the period |  | 101,490,000 |  |  |  | 97,941,000
Other Pension Plan |  |  |  |  |  |
Schedule of Pension and Other Postretirement Benefits Changes in Benefit Obligation and Fair Value of Plan Assets [Line Items] |  |  |  |  |  |
Actuarial (gain) loss |  |  |  |  | 554,000 |
Current liabilities |  |  | (282,000) | (282,000) |  |
Noncurrent liabilities |  |  | (2,642,000) | (2,642,000) |  |
Net amount recognized |  |  | (2,924,000) | (2,924,000) |  |
Other Pension Plan | 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 |  |  | 461,000 |  | 377,000 |
Participant contributions |  |  | 65,000 |  | 218,000 |
Benefits paid |  |  | (526,000) |  | (595,000) |
Unfunded status at end of the period |  |  | (2,924,000) |  |  |
Other Pension Plan | Predecessor |  |  |  |  |  |
Schedule of Pension and Other Postretirement Benefits Changes in Benefit Obligation and Fair Value of Plan Assets [Line Items] |  |  |  |  |  |
Actuarial (gain) loss |  | (335,000) |  |  |  | (1,138,000)
Current liabilities |  | (418,000) |  |  |  | (418,000)
Noncurrent liabilities |  | (4,399,000) |  |  |  | (4,393,000)
Net amount recognized |  | (4,817,000) |  |  |  | (4,811,000)
Other Pension Plan | Predecessor | 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 |  | 288,000 |  |  |  | 759,000
Participant contributions |  | 58,000 |  |  |  | 411,000
Benefits paid |  | (346,000) |  |  |  | (1,170,000)
Unfunded status at end of the period |  | (4,817,000) |  |  |  | (4,811,000)
Other Pension Plan | 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 |  |  | 4,817,000 |  | 2,924,000 |
Service cost |  |  | 29,000 |  | 61,000 |
Interest cost |  |  | 75,000 |  | 117,000 |
Participant contributions |  |  | 65,000 |  | 218,000 |
Plan amendment |  |  | (1,861,000) |  | (2,954,000) |
Benefits paid |  |  | (526,000) |  | (595,000) |
Actuarial (gain) loss |  |  | 325,000 |  | $ 229,000 |
Benefit obligation at end of the period |  |  | $ 2,924,000 | 2,924,000 |  |
Other Pension Plan | 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 |  | 4,811,000 |  | $ 4,811,000 |  | 5,573,000
Service cost |  | 23,000 |  |  |  | 81,000
Interest cost |  | 64,000 |  |  |  | 201,000
Participant contributions |  | 58,000 |  |  |  | 411,000
Benefits paid |  | (346,000) |  |  |  | (1,170,000)
Actuarial (gain) loss |  | 207,000 |  |  |  | (285,000)
Benefit obligation at end of the period |  | $ 4,817,000 |  |  |  | $ 4,811,000
[1] | The actuarial gain in the twelve months ended December 31, 2018 was primarily attributable to an increase in the discount rate.

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