Postretirement Benefit Plans - Defined Contribution Expenses for Company's Qualified Defined Contribution Plans and Statutory Profit Sharing Contributions (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Defined Contribution Plan Disclosure [Line Items]
Total defined contribution expense	$ 10,949	$ 13,832	$ 13,215
Retirement Contributions [Member]
Defined Contribution Plan Disclosure [Line Items]
Total defined contribution expense	8,930	8,556	8,134
Profit Sharing Contributions [Member]
Defined Contribution Plan Disclosure [Line Items]
Total defined contribution expense	$ 2,019	$ 5,276	$ 5,081