XML 120 R102.htm IDEA: XBRL DOCUMENT
v3.25.0.1

Benefit Plans - Supplemental Executive Retirement Plan (Details) - USD ($) $ in Millions | 12 Months Ended |
--- | --- | ---
Dec. 31, 2024 | Dec. 31, 2023
Defined Benefit Plan Disclosure [Line Items] |  |
Percentage of salary paid upon retirement | 25.00% |
Period before ratable vesting begins | 5 years |
Age ratable vesting ends | 65 years |
Liability under the Salary Continuation Plan | $ 4.6 | $ 4.5
Minimum |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Payment period determined by service period | 5 years |
Maximum |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Payment period determined by service period | 15 years |

X
- Definition Defined Benefit Plan, Payment Period Determined By Service Period + References No definition available. + Details
Name: | bmrc_DefinedBenefitPlanPaymentPeriodDeterminedByServicePeriod
Namespace Prefix: | bmrc_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Definition Defined Benefit Plan, Percentage of Salary Paid upon Retirement + References No definition available. + Details
Name: | bmrc_DefinedBenefitPlanPercentageOfSalaryPaidUponRetirement
Namespace Prefix: | bmrc_
Data Type: | dtr-types1:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Defined Benefits Plan, Age Ratable Vesting Ends + References No definition available. + Details
Name: | bmrc_DefinedBenefitsPlanAgeRatableVestingEnds
Namespace Prefix: | bmrc_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Definition Defined Benefits Plan, Period Before Ratable Vesting Begins + References No definition available. + Details
Name: | bmrc_DefinedBenefitsPlanPeriodBeforeRatableVestingBegins
Namespace Prefix: | bmrc_
Data Type: | xbrli:durationItemType
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_DefinedBenefitPlanDisclosureLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount of liability, recognized in statement of financial position, for defined benefit pension and other postretirement plans. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Topic 942 -SubTopic 210 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03(15)) -Publisher FASB -URI https://asc.fasb.org/1943274/2147478546/942-210-S99-1 Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 944 -SubTopic 210 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-03(a)(15)(a)) -Publisher FASB -URI https://asc.fasb.org/1943274/2147478777/944-210-S99-1 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Topic 715 -SubTopic 20 -Name Accounting Standards Codification -Section 45 -Paragraph 3 -Publisher FASB -URI https://asc.fasb.org/1943274/2147480535/715-20-45-3 Reference 4: http://www.xbrl.org/2003/role/disclosureRef -Topic 715 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 1 -Subparagraph (c) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480506/715-20-50-1 + Details
Name: | us-gaap_PensionAndOtherPostretirementDefinedBenefitPlansLiabilitiesCurrentAndNoncurrent
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

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: |