Consolidated Statements of Comprehensive Income (Loss) (Unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Statement Of Income And Comprehensive Income [Abstract]
Net income, Before tax amount	$ 3,821	$ 3,978	$ 11,839	$ 10,904
Net unrealized holding gains (losses) on available-for-sale securities:
Unrealized holding gains (losses) arising during the period, Before tax amount	1,189	(1,770)	9,677	(8,033)
Reclassification adjustment for gains included in net income, Before tax amount	(3)		36	(3)
Other comprehensive income (loss), Before tax amount	1,186	(1,770)	9,713	(8,036)
Unrealized holding gains (losses) arising during the period, Tax expense (benefit)	250	(372)	2,033	(1,687)
Reclassification adjustment for gains included in net income, Tax expense (benefit)			8	(1)
Other comprehensive income (loss), Tax expense (benefit)	250	(372)	2,041	(1,688)
Unrealized holding gains (losses) arising during the period, Net of tax amount	939	(1,398)	7,644	(6,346)
Reclassification adjustment for gains included in net income, Net of tax amount	(3)		28	(2)
Other comprehensive income (loss), Net of tax amount	936	(1,398)	7,672	(6,348)
Total comprehensive income (loss), Before tax amount	5,007	2,208	21,552	2,868
Tax expense (benefit)	731	767	2,227	1,896
Total comprehensive income (loss), Tax expense (benefit)	981	395	4,268	208
Net income	3,090	3,211	9,612	9,008
Total comprehensive income (loss), Net of tax amount	$ 4,026	$ 1,813	$ 17,284	$ 2,660