Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Statement Of Income And Comprehensive Income [Abstract]
Net income, Before tax amount	$ 5,207	$ 4,692	$ 4,932	$ (186)	$ 3,368	$ 3,821	$ 3,822	$ 4,196	$ 14,645	$ 15,207	$ 12,892
Net unrealized holding gains on securities:
Unrealized holding (losses) gains arising during the period, Before tax amount									6,850	9,327	(3,156)
Reclassification adjustment for (gains) losses included in net income, Before tax amount									(24)	26	(3)
Other comprehensive income (loss), Before tax amount									6,826	9,353	(3,159)
Unrealized holding (losses) gains arising during the period, Tax expense (benefit)									1,439	1,959	(663)
Reclassification adjustment for (gains) losses included in net income, Tax expense (benefit)									(5)	5	(1)
Other comprehensive income (loss), Tax expense (benefit)									1,434	1,964	(664)
Unrealized holding (losses) gains arising during the period, Net of tax amount									5,411	7,368	(2,493)
Reclassification adjustment for (gains) losses included in net income, Net of tax amount									(19)	21	(2)
Other comprehensive income (loss), Net of tax amount									5,392	7,389	(2,495)
Total comprehensive income, Before tax amount									21,471	24,560	9,733
Tax expense (benefit)	1,056	914	998	(406)	623	731	679	817	2,562	2,850	1,557
Total comprehensive income, Tax expense (benefit)									3,996	4,814	893
Net income	$ 4,151	$ 3,778	$ 3,934	$ 220	$ 2,745	$ 3,090	$ 3,143	$ 3,379	12,083	12,357	11,335
Total comprehensive income, Net of tax amount									$ 17,475	$ 19,746	$ 8,840