Loans Receivable and Related Allowance for Loan Losses - Impaired Loans by Class (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2016	Dec. 31, 2015
Impaired Loans with Specific Allowance
Unpaid Principal Balance	$ 1,313	$ 1,185
Recorded Investment	1,280	1,185
Related Allowance	120	110
Average Recorded Investment	677	3,424
Interest Income Recognized in Period	29	130
Cash Basis Interest Recognized in Period	6	114
Impaired Loans with No Specific Allowance
Unpaid Principal Balance	727	1,221
Recorded Investment	553	822
Average Recorded Investment	1,080	1,180
Interest Income Recognized in Period	5	59
Cash Basis Interest Recognized in Period	5	50
Residential first mortgages
Impaired Loans with Specific Allowance
Unpaid Principal Balance	168	169
Recorded Investment	135	169
Related Allowance	19	29
Average Recorded Investment	119	170
Interest Income Recognized in Period	6	6
Cash Basis Interest Recognized in Period	6	6
Impaired Loans with No Specific Allowance
Unpaid Principal Balance	0	0
Recorded Investment	0	0
Average Recorded Investment	23	45
Interest Income Recognized in Period	0	7
Cash Basis Interest Recognized in Period	0	7
Home equity loans and lines of credit
Impaired Loans with Specific Allowance
Unpaid Principal Balance	0	0
Recorded Investment	0	0
Related Allowance	0	0
Average Recorded Investment	0	0
Interest Income Recognized in Period	0	0
Cash Basis Interest Recognized in Period	0	0
Impaired Loans with No Specific Allowance
Unpaid Principal Balance	0	0
Recorded Investment	0	0
Average Recorded Investment	0	0
Interest Income Recognized in Period	0	0
Cash Basis Interest Recognized in Period	0	0
Commercial real estate
Impaired Loans with Specific Allowance
Unpaid Principal Balance	557	93
Recorded Investment	557	93
Related Allowance	95	5
Average Recorded Investment	130	1,613
Interest Income Recognized in Period	23	12
Cash Basis Interest Recognized in Period	0	9
Impaired Loans with No Specific Allowance
Unpaid Principal Balance	631	1,145
Recorded Investment	457	746
Average Recorded Investment	735	1,069
Interest Income Recognized in Period	3	49
Cash Basis Interest Recognized in Period	3	40
Commercial business
Impaired Loans with Specific Allowance
Unpaid Principal Balance	588	923
Recorded Investment	588	923
Related Allowance	6	76
Average Recorded Investment	428	1,641
Interest Income Recognized in Period	0	112
Cash Basis Interest Recognized in Period	0	99
Impaired Loans with No Specific Allowance
Unpaid Principal Balance	96	76
Recorded Investment	96	76
Average Recorded Investment	322	66
Interest Income Recognized in Period	2	3
Cash Basis Interest Recognized in Period	2	3
Consumer
Impaired Loans with Specific Allowance
Unpaid Principal Balance	0	0
Recorded Investment	0	0
Related Allowance	0	0
Average Recorded Investment	0	0
Interest Income Recognized in Period	0	0
Cash Basis Interest Recognized in Period	0	0
Impaired Loans with No Specific Allowance
Unpaid Principal Balance	0	0
Recorded Investment	0	0
Average Recorded Investment	0	0
Interest Income Recognized in Period	0	0
Cash Basis Interest Recognized in Period	$ 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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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Recorded Investment
-URI http://asc.fasb.org/extlink&oid=65880944

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 15
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Amount of average investment of impaired financing receivables for which there is no related allowance for credit losses.

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
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-URI http://asc.fasb.org/extlink&oid=66008989&loc=d3e5258-111524

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Unpaid principal balance of impaired financing receivables for which there is a related allowance for credit losses.

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