Loans Receivable and Related Allowance for Loan Losses - Nonaccrual Loans by Aging Category (Details) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total	$ 2,811	$ 3,278
Not Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total	1,040	1,100
30-59 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total	388	77
60-89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total	17	557
90 Days and Greater Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total	1,366	1,544
Residential first mortgages
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total	759	1,126
Residential first mortgages | Not Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total	71	72
Residential first mortgages | 30-59 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total	388	77
Residential first mortgages | 60-89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total	0	0
Residential first mortgages | 90 Days and Greater Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total	300	977
Home equity loans and lines of credit
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total	451	340
Home equity loans and lines of credit | Not Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total	0	0
Home equity loans and lines of credit | 30-59 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total	0	0
Home equity loans and lines of credit | 60-89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total	17	0
Home equity loans and lines of credit | 90 Days and Greater Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total	434	340
Commercial real estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total	1,001	1,073
Commercial real estate | Not Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total	369	397
Commercial real estate | 30-59 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total	0	0
Commercial real estate | 60-89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total	0	557
Commercial real estate | 90 Days and Greater Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total	632	119
Commercial business
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total	600	726
Commercial business | Not Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total	600	631
Commercial business | 30-59 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total	0	0
Commercial business | 60-89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total	0	0
Commercial business | 90 Days and Greater Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total	0	95
Consumer
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total	0	13
Consumer | Not Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total	0	0
Consumer | 30-59 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total	0	0
Consumer | 60-89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total	0	0
Consumer | 90 Days and Greater Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total	$ 0	$ 13