Loans - Age Analysis of Past Due Loans Segregated by Portfolio Segment and Class of Loans (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017	Sep. 30, 2017
Recorded Investment, Past Due [Line Items]
Total Past Due	$ 13,881	$ 12,154
Current	607,178	569,090
Total Loans Receivable	621,059	581,244	$ 566,903
30-59 Days Past Due [Member]
Recorded Investment, Past Due [Line Items]
Total Past Due	8,477	4,259
60-89 Days Past Due [Member]
Recorded Investment, Past Due [Line Items]
Total Past Due	934	3,311
90 Days and Over [Member]
Recorded Investment, Past Due [Line Items]
Total Past Due	4,470	4,584
Residential Mortgage Loans [Member]
Recorded Investment, Past Due [Line Items]
Total Past Due	2,549	4,052
Current	233,169	218,299
Total Loans Receivable	235,718	222,351
Residential Mortgage Loans [Member] | 30-59 Days Past Due [Member]
Recorded Investment, Past Due [Line Items]
Total Past Due	530	1,196
Residential Mortgage Loans [Member] | 60-89 Days Past Due [Member]
Recorded Investment, Past Due [Line Items]
Total Past Due	239	925
Residential Mortgage Loans [Member] | 90 Days and Over [Member]
Recorded Investment, Past Due [Line Items]
Total Past Due	1,780	1,931
Residential Mortgage Loans [Member] | 1-4 Family First Lien Residential Mortgages [Member]
Recorded Investment, Past Due [Line Items]
Total Past Due	2,549	4,052
Current	229,281	212,741
Total Loans Receivable	231,830	216,793	209,147
Residential Mortgage Loans [Member] | 1-4 Family First Lien Residential Mortgages [Member] | 30-59 Days Past Due [Member]
Recorded Investment, Past Due [Line Items]
Total Past Due	530	1,196
Residential Mortgage Loans [Member] | 1-4 Family First Lien Residential Mortgages [Member] | 60-89 Days Past Due [Member]
Recorded Investment, Past Due [Line Items]
Total Past Due	239	925
Residential Mortgage Loans [Member] | 1-4 Family First Lien Residential Mortgages [Member] | 90 Days and Over [Member]
Recorded Investment, Past Due [Line Items]
Total Past Due	1,780	1,931
Residential Mortgage Loans [Member] | Construction [Member]
Recorded Investment, Past Due [Line Items]
Total Past Due	0	0
Current	3,888	5,558
Total Loans Receivable	3,888	5,558
Residential Mortgage Loans [Member] | Construction [Member] | 30-59 Days Past Due [Member]
Recorded Investment, Past Due [Line Items]
Total Past Due	0	0
Residential Mortgage Loans [Member] | Construction [Member] | 60-89 Days Past Due [Member]
Recorded Investment, Past Due [Line Items]
Total Past Due	0	0
Residential Mortgage Loans [Member] | Construction [Member] | 90 Days and Over [Member]
Recorded Investment, Past Due [Line Items]
Total Past Due	0	0
Commercial Loans [Member]
Recorded Investment, Past Due [Line Items]
Total Past Due	10,668	7,367
Current	322,278	296,945
Total Loans Receivable	332,946	304,312
Commercial Loans [Member] | 30-59 Days Past Due [Member]
Recorded Investment, Past Due [Line Items]
Total Past Due	7,586	2,777
Commercial Loans [Member] | 60-89 Days Past Due [Member]
Recorded Investment, Past Due [Line Items]
Total Past Due	622	2,262
Commercial Loans [Member] | 90 Days and Over [Member]
Recorded Investment, Past Due [Line Items]
Total Past Due	2,460	2,328
Commercial Loans [Member] | Real Estate [Member]
Recorded Investment, Past Due [Line Items]
Total Past Due	6,133	4,321
Current	207,170	188,204
Total Loans Receivable	213,303	192,525	187,960
Commercial Loans [Member] | Real Estate [Member] | 30-59 Days Past Due [Member]
Recorded Investment, Past Due [Line Items]
Total Past Due	3,715	720
Commercial Loans [Member] | Real Estate [Member] | 60-89 Days Past Due [Member]
Recorded Investment, Past Due [Line Items]
Total Past Due	385	2,171
Commercial Loans [Member] | Real Estate [Member] | 90 Days and Over [Member]
Recorded Investment, Past Due [Line Items]
Total Past Due	2,033	1,430
Commercial Loans [Member] | Lines of Credit [Member]
Recorded Investment, Past Due [Line Items]
Total Past Due	3,394	1,645
Current	45,102	49,640
Total Loans Receivable	48,496	51,285	53,888
Commercial Loans [Member] | Lines of Credit [Member] | 30-59 Days Past Due [Member]
Recorded Investment, Past Due [Line Items]
Total Past Due	3,354	1,482
Commercial Loans [Member] | Lines of Credit [Member] | 60-89 Days Past Due [Member]
Recorded Investment, Past Due [Line Items]
Total Past Due	0	31
Commercial Loans [Member] | Lines of Credit [Member] | 90 Days and Over [Member]
Recorded Investment, Past Due [Line Items]
Total Past Due	40	132
Commercial Loans [Member] | Other Commercial and Industrial [Member]
Recorded Investment, Past Due [Line Items]
Total Past Due	1,141	1,401
Current	59,843	48,696
Total Loans Receivable	60,984	50,097	43,779
Commercial Loans [Member] | Other Commercial and Industrial [Member] | 30-59 Days Past Due [Member]
Recorded Investment, Past Due [Line Items]
Total Past Due	517	575
Commercial Loans [Member] | Other Commercial and Industrial [Member] | 60-89 Days Past Due [Member]
Recorded Investment, Past Due [Line Items]
Total Past Due	237	60
Commercial Loans [Member] | Other Commercial and Industrial [Member] | 90 Days and Over [Member]
Recorded Investment, Past Due [Line Items]
Total Past Due	387	766
Commercial Loans [Member] | Tax Exempt Loans [Member]
Recorded Investment, Past Due [Line Items]
Total Past Due	0	0
Current	10,163	10,405
Total Loans Receivable	10,163	10,405	11,064
Commercial Loans [Member] | Tax Exempt Loans [Member] | 30-59 Days Past Due [Member]
Recorded Investment, Past Due [Line Items]
Total Past Due	0	0
Commercial Loans [Member] | Tax Exempt Loans [Member] | 60-89 Days Past Due [Member]
Recorded Investment, Past Due [Line Items]
Total Past Due	0	0
Commercial Loans [Member] | Tax Exempt Loans [Member] | 90 Days and Over [Member]
Recorded Investment, Past Due [Line Items]
Total Past Due	0	0
Consumer Loans [Member]
Recorded Investment, Past Due [Line Items]
Total Past Due	664	735
Current	51,731	53,846
Total Loans Receivable	52,395	54,581
Consumer Loans [Member] | 30-59 Days Past Due [Member]
Recorded Investment, Past Due [Line Items]
Total Past Due	361	286
Consumer Loans [Member] | 60-89 Days Past Due [Member]
Recorded Investment, Past Due [Line Items]
Total Past Due	73	124
Consumer Loans [Member] | 90 Days and Over [Member]
Recorded Investment, Past Due [Line Items]
Total Past Due	230	325
Consumer Loans [Member] | Home Equity and Junior Liens [Member]
Recorded Investment, Past Due [Line Items]
Total Past Due	257	430
Current	25,728	25,505
Total Loans Receivable	25,985	25,935	25,408
Consumer Loans [Member] | Home Equity and Junior Liens [Member] | 30-59 Days Past Due [Member]
Recorded Investment, Past Due [Line Items]
Total Past Due	102	94
Consumer Loans [Member] | Home Equity and Junior Liens [Member] | 60-89 Days Past Due [Member]
Recorded Investment, Past Due [Line Items]
Total Past Due	9	74
Consumer Loans [Member] | Home Equity and Junior Liens [Member] | 90 Days and Over [Member]
Recorded Investment, Past Due [Line Items]
Total Past Due	146	262
Consumer Loans [Member] | Other Consumer [Member]
Recorded Investment, Past Due [Line Items]
Total Past Due	407	305
Current	26,003	28,341
Total Loans Receivable	26,410	28,646	$ 29,733
Consumer Loans [Member] | Other Consumer [Member] | 30-59 Days Past Due [Member]
Recorded Investment, Past Due [Line Items]
Total Past Due	259	192
Consumer Loans [Member] | Other Consumer [Member] | 60-89 Days Past Due [Member]
Recorded Investment, Past Due [Line Items]
Total Past Due	64	50
Consumer Loans [Member] | Other Consumer [Member] | 90 Days and Over [Member]
Recorded Investment, Past Due [Line Items]
Total Past Due	$ 84	$ 63