Retirement Plans - Schedule of Net Benefit Costs (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Compensation And Retirement Disclosure [Abstract]
Interest cost	$ 206	$ 251	$ 618	$ 753
Net amortization	96	72	290	216
Net periodic pension cost	$ 302	$ 323	$ 908	$ 969