Postretirement Benefits - Activity for the SERP (Detail) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Dec. 31, 2021
Retirement Benefits [Abstract]
Premiums paid for insurance coverage	$ 443	$ 2,193
Total investments:
Company owned life insurance	54,274		$ 52,791
Exchange traded funds	68,643		87,133
Total investments of SERP	$ 122,917		$ 139,924