Segment and Related Information (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2017 USD ($) segment	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)
Segment Reporting [Abstract]
Number of reportable segments | segment	2
Segment Reporting Information [Line Items]
Interest income	$ 63,038	$ 56,170	$ 55,169
Interest expense	7,291	6,316	5,904
Noninterest income	14,227	13,505	13,287
Income (loss) before income taxes	26,075	23,308	21,059
Net income (loss)	15,249	16,301	15,039
Depreciation and amortization	2,405	2,856	3,034
Total assets	1,816,078	1,678,638	1,547,599
Goodwill	43,872	43,872	43,872
Capital expenditures	2,648	3,613	1,474
Operating Segments | Community Banking
Segment Reporting Information [Line Items]
Interest income	62,697	56,076	55,109
Interest expense	6,263	5,438	5,144
Noninterest income	9,224	8,848	8,386
Income (loss) before income taxes	24,828	22,230	19,398
Net income (loss)	14,456	15,486	13,793
Depreciation and amortization	2,393	2,845	3,022
Total assets	1,806,647	1,669,629	1,545,377
Goodwill	43,872	43,872	43,872
Capital expenditures	2,637	3,609	1,453
Operating Segments | Trust and Investment Services
Segment Reporting Information [Line Items]
Interest income	0	0	0
Interest expense	0	0	0
Noninterest income	4,756	4,634	4,881
Income (loss) before income taxes	2,521	2,623	2,737
Net income (loss)	1,486	1,835	1,956
Depreciation and amortization	12	11	12
Total assets	0	0	0
Goodwill	0	0	0
Capital expenditures	11	4	21
Other
Segment Reporting Information [Line Items]
Interest income	341	94	60
Interest expense	1,028	878	760
Noninterest income	247	23	20
Income (loss) before income taxes	(1,274)	(1,545)	(1,076)
Net income (loss)	(693)	(1,020)	(710)
Depreciation and amortization	0	0	0
Total assets	236,644	229,241	225,533
Goodwill	0	0	0
Capital expenditures	0	0	0
Intersegment Eliminations
Segment Reporting Information [Line Items]
Interest income	0	0	0
Interest expense	0	0	0
Noninterest income	0	0	0
Income (loss) before income taxes	0	0	0
Net income (loss)	0	0	0
Depreciation and amortization	0	0	0
Total assets	(227,213)	(220,232)	(223,311)
Goodwill	0	0	0
Capital expenditures	$ 0	$ 0	$ 0