Employee Benefit Plans - Summary of Restricted Shares Issued, Vested and Forfeited (Detail)	12 Months Ended
	Dec. 31, 2022 Employee shares	Dec. 31, 2021 Employee shares	Dec. 31, 2020 Employee shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted stock awards, shares issued	56,496	48,750	37,382
Restricted Stock Awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted stock awards, shares issued	56,496	48,750	37,382
Restricted shares vested	26,900	18,845	23,491
Restricted shares awarded due to retirement	3,775	4,425	10,890
Restricted shares awarded for other			1,050
Restricted shares forfeited	8,000	2,575	2,175
Restricted shares issued | Employee	109	96	92
Restricted shares vested | Employee	60	50	58
Restricted shares awarded due to retirement | Employee	3	7	8
Restricted shares awarded for other | Employee			1
Restricted shares forfeited | Employee	9	4	5