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Employee Benefit Plans - Summary of Retirement Plan Expense (Detail) - USD ($) $ in Thousands | 12 Months Ended
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Dec. 31, 2020 | Dec. 31, 2019 | Dec. 31, 2018
Schedule of Employee Benefit Plans [Line Items] |  |  |
Retirement plan expense | $ 40,786 | $ 51,332 | $ 42,937
Defined benefit pension plans |  |  |
Schedule of Employee Benefit Plans [Line Items] |  |  |
Retirement plan expense | 9,670 | 9,815 | 12,366
Defined contribution retirement plans |  |  |
Schedule of Employee Benefit Plans [Line Items] |  |  |
Retirement plan expense | 26,697 | 32,743 | 35,318
Postretirement benefit plans |  |  |
Schedule of Employee Benefit Plans [Line Items] |  |  |
Retirement plan expense | (1,972) | (2,220) | (2,148)
Deferred compensation and excess benefit plans |  |  |
Schedule of Employee Benefit Plans [Line Items] |  |  |
Retirement plan expense | $ 6,391 | $ 10,994 | $ (2,599)

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- Definition Schedule of Employee Benefit Plans [Line Items] + References No definition available. + Details
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- Definition Amount of cost (reversal of cost) for pension and other postretirement benefits. + References No definition available. + Details
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- Details
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- Details
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