Loans Receivable and Related Allowance for Loan Losses - Impaired Loans by Class (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended	12 Months Ended
Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016	Dec. 31, 2016
Impaired Loans with Specific Allowance
Unpaid Principal Balance	$ 76	$ 78	$ 76	$ 78	$ 1,313
Recorded Investment	76	78	76	78	1,280
Related Allowance	8	19	8	19	120
Average Recorded Investment	76	393	478	657	677
Interest Income Recognized in Period	1	1	2	2	29
Cash Basis Interest Recognized in Period	1	1	2	2	6
Impaired Loans with No Specific Allowance
Unpaid Principal Balance	2,227	2,003	2,227	2,003	727
Recorded Investment	1,941	1,571	1,941	1,571	553
Average Recorded Investment	1,972	1,280	1,499	1,127	1,080
Interest Income Recognized in Period	3	1	6	4	5
Cash Basis Interest Recognized in Period	3	1	6	4	5
Residential first mortgages
Impaired Loans with Specific Allowance
Unpaid Principal Balance	76	78	76	78	168
Recorded Investment	76	78	76	78	135
Related Allowance	8	19	8	19	19
Average Recorded Investment	76	78	96	109	119
Interest Income Recognized in Period	1	1	2	2	6
Cash Basis Interest Recognized in Period	1	1	2	2	6
Impaired Loans with No Specific Allowance
Unpaid Principal Balance	478	91	478	91	0
Recorded Investment	366	58	366	58	0
Average Recorded Investment	369	58	246	38	23
Interest Income Recognized in Period	3	0	4	2	0
Cash Basis Interest Recognized in Period	3	0	4	2	0
Home equity loans and lines of credit
Impaired Loans with Specific Allowance
Unpaid Principal Balance	0	0	0	0	0
Recorded Investment	0	0	0	0	0
Related Allowance	0	0	0	0	0
Average Recorded Investment	0	0	0	0	0
Interest Income Recognized in Period	0	0	0	0	0
Cash Basis Interest Recognized in Period	0	0	0	0	0
Impaired Loans with No Specific Allowance
Unpaid Principal Balance	0	0	0	0	0
Recorded Investment	0	0	0	0	0
Average Recorded Investment	0	0	0	0	0
Interest Income Recognized in Period	0	0	0	0	0
Cash Basis Interest Recognized in Period	0	0	0	0	0
Commercial real estate
Impaired Loans with Specific Allowance
Unpaid Principal Balance	0	0	0	0	557
Recorded Investment	0	0	0	0	557
Related Allowance	0	0	0	0	95
Average Recorded Investment	0	0	186	31	130
Interest Income Recognized in Period	0	0	0	0	23
Cash Basis Interest Recognized in Period	0	0	0	0	0
Impaired Loans with No Specific Allowance
Unpaid Principal Balance	1,149	1,222	1,149	1,222	631
Recorded Investment	975	823	975	823	457
Average Recorded Investment	983	840	807	809	735
Interest Income Recognized in Period	0	0	1	1	3
Cash Basis Interest Recognized in Period	0	0	1	1	3
Commercial business
Impaired Loans with Specific Allowance
Unpaid Principal Balance	0	0	0	0	588
Recorded Investment	0	0	0	0	588
Related Allowance	0	0	0	0	6
Average Recorded Investment	0	315	196	517	428
Interest Income Recognized in Period	0	0	0	0	0
Cash Basis Interest Recognized in Period	0	0	0	0	0
Impaired Loans with No Specific Allowance
Unpaid Principal Balance	600	690	600	690	96
Recorded Investment	600	690	600	690	96
Average Recorded Investment	620	382	446	280	322
Interest Income Recognized in Period	0	1	1	1	2
Cash Basis Interest Recognized in Period	0	1	1	1	2
Consumer
Impaired Loans with Specific Allowance
Unpaid Principal Balance	0	0	0	0	0
Recorded Investment	0	0	0	0	0
Related Allowance	0	0	0	0	0
Average Recorded Investment	0	0	0	0	0
Interest Income Recognized in Period	0	0	0	0	0
Cash Basis Interest Recognized in Period	0	0	0	0	0
Impaired Loans with No Specific Allowance
Unpaid Principal Balance	0	0	0	0	0
Recorded Investment	0	0	0	0	0
Average Recorded Investment	0	0	0	0	0
Interest Income Recognized in Period	0	0	0	0	0
Cash Basis Interest Recognized in Period	$ 0	$ 0	$ 0	$ 0	$ 0

Impaired Financing Receivable, with No Related Allowance [Abstract]

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Impaired Financing Receivable, with Related Allowance [Abstract]

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Amount of allowance for credit losses related to recorded investment.

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-Publisher FASB
-Name Accounting Standards Codification
-Glossary Recorded Investment
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-Publisher FASB
-Name Accounting Standards Codification
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