Income Taxes - Income Tax Expense from Operations from the Amount Computed by Applying the U.S. Federal Income Tax Statutory Rate of 21% to Income Before Income Taxes (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Income Tax Disclosure [Abstract]
Income tax computed at federal statutory tax rate	$ 14,206	$ 16,684	$ 22,453
Tax-exempt interest, net	(2,268)	(2,511)	(3,226)
State income tax	3	911	1,080
Dividends received deduction	(134)	(107)	(89)
Valuation allowance	(17)	(1,803)	46
Prior year adjustments	14	344	3
Other	240	175	50
Income tax expense, Total	$ 12,044	$ 13,693	$ 20,317