Loans - Analysis of the age of the loan delinquencies by type and by amount past due (Details 2) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	$ 763	$ 136
Current	242,384	226,933
Loans	243,147	227,069
30-59 Days Past Due And Accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	618	136
60-89 Days Past Due And Accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	108
90 Days and Over
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	37
Real estate loans:
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	695	89
Current	239,861	224,958
Loans	240,556	225,047
Real estate loans: | 30-59 Days Past Due And Accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	618	89
Real estate loans: | 60-89 Days Past Due And Accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	40
Real estate loans: | 90 Days and Over
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	37
Real estate loans: | Secured by one-to-four family residences
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	482	89
Current	196,198	188,484
Loans	196,680	188,573
Real estate loans: | Secured by one-to-four family residences | 30-59 Days Past Due And Accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	405	89
Real estate loans: | Secured by one-to-four family residences | 60-89 Days Past Due And Accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	40
Real estate loans: | Secured by one-to-four family residences | 90 Days and Over
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	37
Real estate loans: | Secured by multi-family residences
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due
Current	6,217	5,103
Loans	6,217	5,103
Real estate loans: | Secured by multi-family residences | 30-59 Days Past Due And Accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due
Real estate loans: | Secured by multi-family residences | 60-89 Days Past Due And Accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due
Real estate loans: | Secured by multi-family residences | 90 Days and Over
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due
Real estate loans: | Construction
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due
Current	9,807	6,134
Loans	9,807	6,134
Real estate loans: | Construction | 30-59 Days Past Due And Accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due
Real estate loans: | Construction | 60-89 Days Past Due And Accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due
Real estate loans: | Construction | 90 Days and Over
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due
Real estate loans: | Commercial
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due
Current	10,608	8,440
Loans	10,608	8,440
Real estate loans: | Commercial | 30-59 Days Past Due And Accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due
Real estate loans: | Commercial | 60-89 Days Past Due And Accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0
Real estate loans: | Commercial | 90 Days and Over
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due
Real estate loans: | Home equity lines of credit
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	213
Current	17,031	16,797
Loans	17,244	16,797
Real estate loans: | Home equity lines of credit | 30-59 Days Past Due And Accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	213
Real estate loans: | Home equity lines of credit | 60-89 Days Past Due And Accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due
Real estate loans: | Home equity lines of credit | 90 Days and Over
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due
Other Loans Portfolio Segment | Commercial & industrial loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	68	47
Current	2,450	1,900
Loans	2,518	1,947
Other Loans Portfolio Segment | Commercial & industrial loans | 30-59 Days Past Due And Accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due		47
Other Loans Portfolio Segment | Commercial & industrial loans | 60-89 Days Past Due And Accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	68
Other Loans Portfolio Segment | Commercial & industrial loans | 90 Days and Over
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due
Other Loans Portfolio Segment | Other loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due
Current	73	75
Loans	73	75
Other Loans Portfolio Segment | Other loans | 30-59 Days Past Due And Accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due
Other Loans Portfolio Segment | Other loans | 60-89 Days Past Due And Accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due
Other Loans Portfolio Segment | Other loans | 90 Days and Over
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due