Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands		3 Months Ended		6 Months Ended
		Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Statement Of Income And Comprehensive Income [Abstract]
Net income		$ 2,345	$ 2,022	$ 4,339	$ 3,827
Other comprehensive income:
Unrealized gains arising during the period on available-for-sale securities, net of income taxes, respectively		1,480	1,854	1,859	2,220
Reclassification adjustment for net gain on sales of available-for-sale securities included in net income, net of income taxes, respectively	[1]	(8)	(140)	(13)	(140)
Change in defined benefit plans, net of income taxes, respectively	[2]	(1)	(2)	(4)	(116)
Total other comprehensive income		1,471	1,712	1,842	1,964
Total comprehensive income		$ 3,816	$ 3,734	$ 6,181	$ 5,791

[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.