Other Comprehensive Income (Loss) - Amounts Reclassified Out of Each Component of Accumulated Other Comprehensive Loss (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Net gain on sale of securities	$ 0	$ 10	$ 1,786
Other operating expenses	(12,465)	(10,223)	(12,183)
Income taxes	(7,649)	(7,608)	(7,835)
Net income	42,964	39,427	40,546
Reclassification out of Accumulated Other Comprehensive Loss [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Net income	0	8	(189)
Unrealized Gains (Losses) on Available-for-Sale Securities [Member] | Reclassification out of Accumulated Other Comprehensive Loss [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Net gain on sale of securities	0	10	1
Income taxes	0	(2)	0
Net income	0	8	1
Accumulated Defined Benefit Plans Adjustment, Actuarial Losses [Member] | Reclassification out of Accumulated Other Comprehensive Loss [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Other operating expenses	0	0	(240)
Income taxes	0	0	50
Net income	$ 0	$ 0	$ (190)