Loans Loan Categories and Past Due Loans (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018	Mar. 31, 2018
Financing Receivable, Recorded Investment, Aging [Abstract]
Recorded investment, past due	$ 10,177	$ 13,177	$ 8,298
Current Loans	2,225,031	2,183,038	1,984,739
Total Loans	2,235,208	2,196,215	1,993,037
Loans 90 or More Days Past Due and Still Accruing Interest	64	1,225	0
Nonaccrual Loans	5,143	4,159	4,470
Financing Receivables, 30 to 59 Days Past Due
Financing Receivable, Recorded Investment, Aging [Abstract]
Recorded investment, past due	6,479	5,879	5,585
Financing Receivables, 60 to 89 Days Past Due
Financing Receivable, Recorded Investment, Aging [Abstract]
Recorded investment, past due	1,594	4,093	1,292
Financing Receivables, Equal to Greater than 90 Days Past Due
Financing Receivable, Recorded Investment, Aging [Abstract]
Recorded investment, past due	2,104	3,205	1,421
Commercial
Financing Receivable, Recorded Investment, Aging [Abstract]
Recorded investment, past due	185	170	146
Current Loans	133,091	136,720	127,528
Total Loans	133,276	136,890	127,674
Loans 90 or More Days Past Due and Still Accruing Interest	0	0	0
Nonaccrual Loans	415	403	652
Commercial | Financing Receivables, 30 to 59 Days Past Due
Financing Receivable, Recorded Investment, Aging [Abstract]
Recorded investment, past due	168	121	45
Commercial | Financing Receivables, 60 to 89 Days Past Due
Financing Receivable, Recorded Investment, Aging [Abstract]
Recorded investment, past due	0	49	60
Commercial | Financing Receivables, Equal to Greater than 90 Days Past Due
Financing Receivable, Recorded Investment, Aging [Abstract]
Recorded investment, past due	17	0	41
Commercial Real Estate Portfolio Segment
Financing Receivable, Recorded Investment, Aging [Abstract]
Recorded investment, past due	316	897	963
Current Loans	493,071	483,665	454,095
Total Loans	493,387	484,562	455,058
Loans 90 or More Days Past Due and Still Accruing Interest	0	0	0
Nonaccrual Loans	248	789	807
Commercial Real Estate Portfolio Segment | Financing Receivables, 30 to 59 Days Past Due
Financing Receivable, Recorded Investment, Aging [Abstract]
Recorded investment, past due	208	108	156
Commercial Real Estate Portfolio Segment | Financing Receivables, 60 to 89 Days Past Due
Financing Receivable, Recorded Investment, Aging [Abstract]
Recorded investment, past due	0	0	0
Commercial Real Estate Portfolio Segment | Financing Receivables, Equal to Greater than 90 Days Past Due
Financing Receivable, Recorded Investment, Aging [Abstract]
Recorded investment, past due	108	789	807
Consumer Loans Financing
Financing Receivable, Recorded Investment, Aging [Abstract]
Recorded investment, past due	6,514	8,077	4,676
Current Loans	740,285	711,433	621,964
Total Loans	746,799	719,510	626,640
Loans 90 or More Days Past Due and Still Accruing Interest	0	144	0
Nonaccrual Loans	588	658	441
Consumer Loans Financing | Financing Receivables, 30 to 59 Days Past Due
Financing Receivable, Recorded Investment, Aging [Abstract]
Recorded investment, past due	4,758	5,369	3,673
Consumer Loans Financing | Financing Receivables, 60 to 89 Days Past Due
Financing Receivable, Recorded Investment, Aging [Abstract]
Recorded investment, past due	1,387	2,136	751
Consumer Loans Financing | Financing Receivables, Equal to Greater than 90 Days Past Due
Financing Receivable, Recorded Investment, Aging [Abstract]
Recorded investment, past due	369	572	252
Residential
Financing Receivable, Recorded Investment, Aging [Abstract]
Recorded investment, past due	3,162	4,033	2,513
Current Loans	858,584	851,220	781,152
Total Loans	861,746	855,253	783,665
Loans 90 or More Days Past Due and Still Accruing Interest	64	1,081	0
Nonaccrual Loans	3,892	2,309	2,570
Residential | Financing Receivables, 30 to 59 Days Past Due
Financing Receivable, Recorded Investment, Aging [Abstract]
Recorded investment, past due	1,345	281	1,711
Residential | Financing Receivables, 60 to 89 Days Past Due
Financing Receivable, Recorded Investment, Aging [Abstract]
Recorded investment, past due	207	1,908	481
Residential | Financing Receivables, Equal to Greater than 90 Days Past Due
Financing Receivable, Recorded Investment, Aging [Abstract]
Recorded investment, past due	$ 1,610	$ 1,844	$ 321