Employee Benefit Plans - Components of Net Periodic Benefit Cost (Credit) (Detail) - Pension Plans [Member] - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Components of Net Periodic Benefit Cost (Credit):
Service cost	$ 226	$ 135
Interest cost	2,115	2,983
Expected return on plan assets	(6,534)	(6,628)
Amortization of:
Prior service cost	30	27
Net actuarial loss (gain)	1,687	2,206
Settlement loss	380	922
Net periodic benefit cost (credit)	$ (2,096)	$ (355)