Loans Receivable and Related Allowance for Loan Losses - Loan Portfolio by Internal Risk Rating System (Details) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total	$ 540,892	$ 520,980
Not Rated
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total	305,675	294,717
Pass
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total	225,333	213,437
Special Mention
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total	1,977	6,003
Substandard
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total	7,907	6,823
Doubtful
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total	0	0
Residential first mortgages
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total	209,694	198,167
Residential first mortgages | Not Rated
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total	208,905	197,041
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	789	1,126
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	90,648	91,359
Home equity loans and lines of credit | Not Rated
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total	89,997	91,017
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	651	342
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	178,024	166,994
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	171,228	161,312
Commercial real estate | Special Mention
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total	1,505	1,077
Commercial real estate | Substandard
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total	5,291	4,605
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	55,753	57,788
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	54,105	52,125
Commercial Business | Special Mention
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total	472	4,926
Commercial Business | Substandard
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total	1,176	737
Commercial Business | Doubtful
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total	0	0
Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total	6,773	6,672
Consumer | Not Rated
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total	6,773	6,659
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	0	13
Consumer | Doubtful
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total	$ 0	$ 0