XML 67 R50.htm IDEA: XBRL DOCUMENT v3.8.0.1
Employee Benefit Plans - Summary of Retirement Plan Expense (Detail) - USD ($)
$ in Thousands
 12 Months Ended
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Schedule of Employee Benefit Plans [Line Items]      
Retirement plan expense $ 56,914 $ 58,096 $ 57,073
Defined benefit pension plans      
Schedule of Employee Benefit Plans [Line Items]      
Retirement plan expense 7,428 13,999 14,779
Defined contribution retirement plans      
Schedule of Employee Benefit Plans [Line Items]      
Retirement plan expense 38,508 37,661 40,673
Postretirement benefit plans      
Schedule of Employee Benefit Plans [Line Items]      
Retirement plan expense 963 1,343 1,396
Deferred compensation and excess benefit plans      
Schedule of Employee Benefit Plans [Line Items]      
Retirement plan expense $ 10,015 $ 5,093 $ 225