XML 71 R53.htm IDEA: XBRL DOCUMENT
v3.25.0.1

Summary of Significant Accounting Policies - Investments in Low Income Housing Tax Credit Funds (Details) | 12 Months Ended
--- | ---
Dec. 31, 2024
Minimum |
Other Ownership Interests [Line Items] |
Affordable housing tax credits, investment, ownership percentage | 1.00%
Maximum |
Other Ownership Interests [Line Items] |
Affordable housing tax credits, investment, ownership percentage | 3.50%

X
- Definition Affordable Housing Tax Credits, Investment, Ownership Percentage + References No definition available. + Details
Name: | bmrc_AffordableHousingTaxCreditsInvestmentOwnershipPercentage
Namespace Prefix: | bmrc_
Data Type: | dtr-types1:percentItemType
Balance Type: | na
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_OtherOwnershipInterestsLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | srt_RangeAxis=srt_MinimumMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_RangeAxis=srt_MaximumMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |