Loans Receivable and Related Allowance for Loan Losses - Classes of Loan Portfolio by Aging Categories (Details) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Financing Receivable, Recorded Investment, Past Due [Line Items]
Accruing Loans Not Past Due	$ 534,760	$ 514,279
Nonaccrual	2,938	3,278
Total Loans	540,892	520,980
30-59 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Accruing Loans Past Due	2,905	3,021
Nonaccrual	433	77
60-89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Accruing Loans Past Due	119	358
Nonaccrual	0	557
90 Days and Greater Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Accruing Loans Past Due	170	44
Nonaccrual	1,472	1,544
Residential first mortgages
Financing Receivable, Recorded Investment, Past Due [Line Items]
Accruing Loans Not Past Due	207,189	194,830
Nonaccrual	742	1,126
Total Loans	209,694	198,167
Residential first mortgages | 30-59 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Accruing Loans Past Due	1,756	1,916
Nonaccrual	394	77
Residential first mortgages | 60-89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Accruing Loans Past Due	7	295
Nonaccrual	0	0
Residential first mortgages | 90 Days and Greater Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Accruing Loans Past Due	0	0
Nonaccrual	277	977
Home equity loans and lines of credit
Financing Receivable, Recorded Investment, Past Due [Line Items]
Accruing Loans Not Past Due	89,722	90,557
Nonaccrual	528	340
Total Loans	90,648	91,359
Home equity loans and lines of credit | 30-59 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Accruing Loans Past Due	265	460
Nonaccrual	0	0
Home equity loans and lines of credit | 60-89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Accruing Loans Past Due	10	0
Nonaccrual	0	0
Home equity loans and lines of credit | 90 Days and Greater Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Accruing Loans Past Due	123	2
Nonaccrual	528	340
Commercial real estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Accruing Loans Not Past Due	176,115	165,318
Nonaccrual	1,027	1,073
Total Loans	178,024	166,994
Commercial real estate | 30-59 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Accruing Loans Past Due	835	561
Nonaccrual	0	0
Commercial real estate | 60-89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Accruing Loans Past Due	0	0
Nonaccrual	0	557
Commercial real estate | 90 Days and Greater Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Accruing Loans Past Due	47	42
Nonaccrual	643	119
Commercial business
Financing Receivable, Recorded Investment, Past Due [Line Items]
Accruing Loans Not Past Due	54,980	56,972
Nonaccrual	641	726
Total Loans	55,753	57,788
Commercial business | 30-59 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Accruing Loans Past Due	32	56
Nonaccrual	39	0
Commercial business | 60-89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Accruing Loans Past Due	100	34
Nonaccrual	0	0
Commercial business | 90 Days and Greater Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Accruing Loans Past Due	0	0
Nonaccrual	24	95
Consumer
Financing Receivable, Recorded Investment, Past Due [Line Items]
Accruing Loans Not Past Due	6,754	6,602
Nonaccrual	0	13
Total Loans	6,773	6,672
Consumer | 30-59 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Accruing Loans Past Due	17	28
Nonaccrual	0	0
Consumer | 60-89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Accruing Loans Past Due	2	29
Nonaccrual	0	0
Consumer | 90 Days and Greater Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Accruing Loans Past Due	0	0
Nonaccrual	$ 0	$ 13