Consolidated Statements of Comprehensive Income (Loss) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Statement Of Income And Comprehensive Income [Abstract]
Net income	$ 4,403	$ 2,779	$ 8,480	$ 3,783
Other comprehensive income (loss):
Unrealized income (losses) arising during the period on available-for-sale securities, net of income taxes impact, respectively	1,179	(368)	2,998	(2,156)
Reclassification adjustment for net gain on sales of available-for-sale securities included in net income, net of income taxes impact, respectively	(14)	(3)	(19)	(81)
Change in defined benefit plans, net of income taxes impact, respectively	(339)	1,343	(346)	1,342
Reclassification adjustment for settlement gains on benefit plans, net of income taxes, respectively	(29)	(300)	(29)	(300)
Total other comprehensive income (loss)	797	672	2,604	(1,195)
Total comprehensive income	$ 5,200	$ 3,451	$ 11,084	$ 2,588