Components of Net Periodic Pension Cost Benefit (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Compensation And Retirement Disclosure [Abstract]
Service cost	$ 725	$ 689	$ 721
Interest cost	4,237	4,063	4,465
Expected return on plan assets	(4,558)	(5,197)	(5,862)
Amortization of actuarial loss	1,533		863
Net periodic cost	$ 1,937	$ (445)	$ 187