Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Statement Of Income And Comprehensive Income [Abstract]
Net income		$ 7,089	$ 7,804	$ 6,528
Other comprehensive income (loss):
Unrealized gains (losses) arising during the period on available for sale securities, net of income taxes of $589, ($1,954), and $80, respectively		1,143	(3,794)	154
Reclassification adjustment for net gain on sales of available for sale securities included in net income, net of income taxes of ($14), ($356), and ($110), respectively (a)	[1]	(28)	(690)	(215)
Change in defined benefit plans, net of income taxes of $3, ($93), and $185, respectively (b)	[2]	5	(181)	360
Total other comprehensive income (loss)		1,120	(4,665)	299
Total comprehensive income		$ 8,209	$ 3,139	$ 6,827

[1] Amounts are included in net gain on sales of investment securities on the Consolidated Statements of Income as a separate component 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