Employee Benefit Plans - Summary of Retirement Plan Expense (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Schedule of Employee Benefit Plans [Line Items]
Retirement plan expense	$ 58,096	$ 57,073	$ 68,244
Defined contribution retirement plans
Schedule of Employee Benefit Plans [Line Items]
Retirement plan expense	37,661	40,673	43,819
Defined benefit pension plans
Schedule of Employee Benefit Plans [Line Items]
Retirement plan expense	13,999	14,779	18,124
Deferred compensation and excess benefit plans
Schedule of Employee Benefit Plans [Line Items]
Retirement plan expense	5,093	225	4,840
Postretirement benefit plans
Schedule of Employee Benefit Plans [Line Items]
Retirement plan expense	$ 1,343	$ 1,396	$ 1,461