Employee Benefit Plans - Components of Net Periodic Benefit Cost (Credit) (Detail) - Pension Plans [Member] - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Components of Net Periodic Benefit Cost (Credit):
Service cost	$ 223	$ 217	$ 635	$ 670
Interest cost	3,716	3,822	11,476	11,861
Expected return on plan assets	(6,697)	(7,315)	(20,596)	(22,681)
Amortization of:
Prior service cost	26		82
Net actuarial loss (gain)	1,220	1,213	3,761	3,736
Settlement loss	2,280		5,802
Net periodic benefit cost (credit)	$ 768	$ (2,063)	$ 1,160	$ (6,414)