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Employee Benefit Plans - Summary of Retirement Plan Expense (Detail) - USD ($) $ in Thousands	12 Months Ended
	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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Schedule of Employee Benefit Plans [Line Items]

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Amount of cost (reversal of cost) for pension and other postretirement benefits.

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