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Summary of Significant Accounting Policies - Narrative (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2015 USD ($) branch contract	Dec. 31, 2014 USD ($)	Dec. 31, 2013 USD ($)
Accounting Policies [Abstract]
Threshold period a past due loan is charged off	90 days
Threshold period a past due overdraft account is charged off	60 days
Derivatives, Fair Value [Line Items]
Advertising costs | $	$ 334	$ 400	$ 490
Interest rate swap | Designated as hedging instrument | Shortcut hedge accounting
Derivatives, Fair Value [Line Items]
Number of instrument rate swap contracts accounted for using hedge accounting | contract	1
Interest rate swap | Designated as hedging instrument | Non-shortcut Hedge Accounting
Derivatives, Fair Value [Line Items]
Number of instrument rate swap contracts accounted for using hedge accounting | contract	6
Marin County
Derivatives, Fair Value [Line Items]
Number of branches	10
Napa County
Derivatives, Fair Value [Line Items]
Number of branches	1
San Francisco
Derivatives, Fair Value [Line Items]
Number of branches	1
Sonoma County
Derivatives, Fair Value [Line Items]
Number of branches	5
Alameda County
Derivatives, Fair Value [Line Items]
Number of branches	3

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Derivative, Number of Instruments Using Hedge Accounting

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- Definition

Threshold Period Past Due For Write-Off Of Deposit Liabilities Reclassified As Loans Receivable

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- Definition

Amount charged to advertising expense for the period, which are expenses incurred with the objective of increasing revenue for a specified brand, product or product line.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 720
-SubTopic 35
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6420018&loc=d3e36677-107848

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- Definition

Represents the number of stores.

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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.

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