Income Taxes - Reconciliation between applicable income taxes and statutory federal tax rate (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Tax amount
Taxes at statutory federal income tax rate	$ 3,329	$ 10,958	$ 14,506
Tax exempt income	(715)	(514)	(556)
State income taxes, net of federal benefits	715	2,297	2,973
Nondeductible items and other	829	(564)	(527)
Applicable income taxes	$ 4,158	$ 12,177	$ 16,396
Percentage of pretax income
Taxes at statutory federal income tax rate (as percentage)	21.00%	21.00%	21.00%
Tax exempt income (as percentage)	(4.50%)	(1.00%)	(0.80%)
State income taxes, net of federal benefits (as percentage)	4.50%	4.40%	4.30%
Nondeductible items and other (as percentage)	5.20%	(1.10%)	(0.80%)
Applicable income taxes (as percentage)	26.20%	23.30%	23.70%