Consolidated Statements of Comprehensive Income (Loss) - 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	$ 4,813	$ 2,164	$ 13,293	$ 5,947
Other comprehensive income (loss):
Unrealized income (losses) arising during the period on available-for-sale securities, net of income taxes impact, respectively	190	(589)	3,188	(2,746)
Reclassification adjustment for net gain on sales of available-for-sale securities included in net income, net of income taxes impact, respectively	(37)	(23)	(56)	(104)
Change in defined benefit plans, net of income taxes impact, respectively	(231)	248	(545)	1,592
Reclassification adjustment for settlement gains and activity related on benefit plans, net of income taxes, respectively	(17)	(93)	(78)	(394)
Total other comprehensive income (loss)	(95)	(457)	2,509	(1,652)
Total comprehensive income	$ 4,718	$ 1,707	$ 15,802	$ 4,295