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Summary of Significant Accounting Policies - Nature of Operations and Basis of Presentation (Details) | Dec. 31, 2020 branch loanProductionOffice
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Marin County |
Product Information [Line Items] |
Number of branches and loan production offices | 10
Napa County |
Product Information [Line Items] |
Number of branches and loan production offices | 2
San Francisco |
Product Information [Line Items] |
Number of branches and loan production offices | 1
Sonoma County |
Product Information [Line Items] |
Number of branches and loan production offices | 5
Alameda County |
Product Information [Line Items] |
Number of branches and loan production offices | 3
Contra Costa County |
Product Information [Line Items] |
Number of branches and loan production offices | loanProductionOffice | 1
San Mateo County |
Product Information [Line Items] |
Number of branches and loan production offices | loanProductionOffice | 1

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