Loans Receivable and Related Allowance for Loan Losses - Loan Portfolio by Internal Risk Rating System (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total	$ 520,980	$ 435,096
Not Rated
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total	294,717	231,853
Pass
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total	213,437	195,279
Special Mention
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total	6,003	1,030
Substandard
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total	6,823	6,934
Doubtful
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total	0	0
Residential first mortgages
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total	198,167	139,305
Residential first mortgages | Not Rated
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total	197,041	138,096
Residential first mortgages | Pass
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total	0	0
Residential first mortgages | Special Mention
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total	0	0
Residential first mortgages | Substandard
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total	1,126	1,209
Residential first mortgages | Doubtful
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total	0	0
Home equity loans and lines of credit
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total	91,359	87,410
Home equity loans and lines of credit | Not Rated
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total	91,017	87,015
Home equity loans and lines of credit | Pass
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total	0	0
Home equity loans and lines of credit | Special Mention
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total	0	0
Home equity loans and lines of credit | Substandard
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total	342	395
Home equity loans and lines of credit | Doubtful
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total	0	0
Commercial real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total	166,994	129,691
Commercial real estate | Not Rated
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total	0	0
Commercial real estate | Pass
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total	161,312	125,539
Commercial real estate | Special Mention
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total	1,077	88
Commercial real estate | Substandard
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total	4,605	4,064
Commercial real estate | Doubtful
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total	0	0
Commercial Business
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total	57,788	71,948
Commercial Business | Not Rated
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total	0	0
Commercial Business | Pass
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total	52,125	69,740
Commercial Business | Special Mention
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total	4,926	942
Commercial Business | Substandard
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total	737	1,266
Commercial Business | Doubtful
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total	0	0
Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total	6,672	6,742
Consumer | Not Rated
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total	6,659	6,742
Consumer | Pass
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total	0	0
Consumer | Special Mention
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total	0	0
Consumer | Substandard
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total	13	0
Consumer | Doubtful
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total	$ 0	$ 0