Income Taxes - Effective Tax Rates Differed from Statutory Federal Income Tax Rate (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Income Tax Disclosure [Abstract]
Income taxes computed at the statutory federal tax rate	$ 10,629	$ 9,878	$ 9,988
Add (subtract) tax effect of:
Nontaxable interest income, net of nondeductible interest expense	(1,938)	(1,666)	(1,315)
Low income housing tax credit	(620)	(679)	(1,402)
Cash surrender value of BOLI	(233)	(207)	(252)
Other	(189)	282	(2)
Income tax expense	$ 7,649	$ 7,608	$ 7,017