Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Statement Of Income And Comprehensive Income [Abstract]
Net income		$ 2,249	$ 1,901	$ 6,588	$ 5,728
Other comprehensive income (loss):
Unrealized (losses) gains arising during the period on available-for-sale securities, net of income taxes, respectively		(1)	(677)	1,858	1,543
Reclassification adjustment for net gain on sales of available-for-sale securities included in net income, net of income taxes, respectively	[1]	(15)	(132)	(28)	(272)
Change in defined benefit plans, net of income taxes, respectively	[2]	(3)	(11)	(7)	(127)
Total other comprehensive income (loss)		(19)	(820)	1,823	1,144
Total comprehensive income		$ 2,230	$ 1,081	$ 8,411	$ 6,872

[1] Amounts are included in net gain on sales of investment securities on the Consolidated Statements of Income as a separate element within total noninterest income.

[2] Amounts are included in the computation of net periodic benefit cost and are included in salaries and employee benefits on the Consolidated Statements of Income as a separate element within total noninterest expense.