XML 50 R39.htm IDEA: XBRL DOCUMENT
v3.20.2

Loans and Allowance for Loan Losses - Troubled Debt Restructuring Narrative (Details) $ in Thousands | 9 Months Ended
--- | ---
Sep. 30, 2020 loan | Sep. 30, 2019 USD ($) loan
Financing Receivable, Troubled Debt Restructuring [Line Items] |  |
Number of loans removed from TDR designation | 0 |
Commercial loans |  |
Financing Receivable, Troubled Debt Restructuring [Line Items] |  |
Number of loans removed from TDR designation |  | 1
Recorded investment of loans removed from TDR designation | $ |  | $ 3

X
- Definition Financing Receivable, Modifications, Removal From Troubled Debt Restructuring, Number Of Contracts + References No definition available. + Details
Name: | bmrc_FinancingReceivableModificationsRemovalFromTroubledDebtRestructuringNumberOfContracts
Namespace Prefix: | bmrc_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | duration

X
- Definition Financing Receivable, Modifications, Removal From Troubled Debt Restructuring, Recorded Investment + References No definition available. + Details
Name: | bmrc_FinancingReceivableModificationsRemovalFromTroubledDebtRestructuringRecordedInvestment
Namespace Prefix: | bmrc_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. + References No definition available. + Details
Name: | us-gaap_FinancingReceivableModificationsLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | us-gaap_FinancingReceivablePortfolioSegmentAxis=us-gaap_CommercialPortfolioSegmentMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |