Fair Value Measurement (Narrative) (Details) - USD ($) $ in Thousands		9 Months Ended	12 Months Ended
Sep. 30, 2017	Sep. 30, 2017	Dec. 31, 2016
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Impaired loans	$ 20,748	$ 20,748	$ 15,141
Impaired loans, allowance for loan loss	$ 1,737	$ 1,737	2,027
Percentage required stock to capital and surplus	6.00%	6.00%
Impairment charges		$ 0	0
Consumer And Other Loans [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Period past due for loan appraisals		90 days
Impaired loans	$ 35	$ 35	43
Impaired loans, allowance for loan loss	35	35	$ 43
Investment In FRB Stock [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Impairment charges		$ 0
FHLBNY [Member] \| Investment In FHLBNY Stock [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Impairment charges	$ 0

Percentage Of Required Federal Reserve Bank Stock To Capital And Surplus

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- Definition

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+ References

No definition available.

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- Definition

Amount of investment of impaired financing receivables with related allowance for credit losses and without a related allowance for credit losses.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 14A
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=84173941&loc=SL6953550-111524

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- Definition

Amount of allowance for credit losses related to recorded investment.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 15
-Subparagraph (a)(3)
-URI http://asc.fasb.org/extlink&oid=84173941&loc=d3e5212-111524

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- Definition

The amount by which the fair value of an investment is less than the amortized cost basis or carrying amount of that investment at the balance sheet date and the decline in fair value is deemed to be other than temporary, before considering whether or not such amount is recognized in earnings or other comprehensive income.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=98514028&loc=d3e3602-108585

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 35
-Paragraph 34
-URI http://asc.fasb.org/extlink&oid=82895926&loc=d3e25351-111560

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- Definition

Threshold period past due for financing receivable to write off as uncollectible, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

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