Retirement Plans - Schedule of Net Benefit Costs (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Compensation And Retirement Disclosure [Abstract]
Interest cost	$ 206	$ 251	$ 412	$ 502
Net amortization	97	72	194	144
Net periodic pension cost	$ 303	$ 323	$ 606	$ 646