Loans and Allowance for Loan Losses - Allowance (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Changes in the allowance for loan losses
Balance at beginning of period	$ 11,242	$ 10,067	$ 10,939	$ 9,878
Charge-offs	(676)	(29)	(676)	(385)
Recoveries	2	8	5	79
Provision (recovery)	600	605	900	1,079
Balance at end of period	11,168	10,651	11,168	10,651
Individually evaluated for impairment	534	1,049	534	1,049
Collectively evaluated for impairment	10,634	9,602	10,634	9,602
Commercial and Non-Residential Real Estate
Changes in the allowance for loan losses
Balance at beginning of period	8,864	7,998	8,605	7,804
Charge-offs	(666)	0	(666)	(324)
Recoveries	1	8	1	10
Provision (recovery)	772	658	1,031	1,174
Balance at end of period	8,971	8,664	8,971	8,664
Individually evaluated for impairment	534	1,049	534	1,049
Collectively evaluated for impairment	8,437	7,615	8,437	7,615
Residential Real Estate
Changes in the allowance for loan losses
Balance at beginning of period	1,417	1,177	1,405	1,119
Charge-offs	0	0	0	(11)
Recoveries	0	0	1	9
Provision (recovery)	(188)	(5)	(177)	55
Balance at end of period	1,229	1,172	1,229	1,172
Individually evaluated for impairment	0	0	0	0
Collectively evaluated for impairment	1,229	1,172	1,229	1,172
Home Equity
Changes in the allowance for loan losses
Balance at beginning of period	704	693	684	705
Charge-offs	0	0	0	0
Recoveries	1	0	2	56
Provision (recovery)	7	(91)	26	(159)
Balance at end of period	712	602	712	602
Individually evaluated for impairment	0	0	0	0
Collectively evaluated for impairment	712	602	712	602
Consumer
Changes in the allowance for loan losses
Balance at beginning of period	257	199	245	250
Charge-offs	(10)	(29)	(10)	(50)
Recoveries	0	0	1	4
Provision (recovery)	9	43	20	9
Balance at end of period	256	213	256	213
Individually evaluated for impairment	0	0	0	0
Collectively evaluated for impairment	$ 256	$ 213	$ 256	$ 213