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: