XML 109 R97.htm IDEA: XBRL DOCUMENT
v3.22.0.1

Benefit Plans - Salary Continuation Plan (Details) $ in Millions | 12 Months Ended |  |
--- | --- | --- | ---
Dec. 31, 2021 USD ($) formerExecutive | Aug. 31, 2021 USD ($) | Dec. 31, 2020 USD ($)
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 | $ | $ 5.3 | $ 1.7 | $ 3.2
Bank Of Napa |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Number of former executives with salary continuation agreements | 4 |  |
Period for fixed annual retirement benefit payments | 10 years |  |
Age ratable vesting ends | 65 years |  |
American River Bank ARB |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Number of former executives with salary continuation agreements | 6 |  |
Period for fixed annual retirement benefit payments | 15 years |  |
Minimum |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Payment period determined by service period | 7 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-types: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 Number Of Former Executives With Salary Continuation Agreements + References No definition available. + Details
Name: | bmrc_NumberOfFormerExecutivesWithSalaryContinuationAgreements
Namespace Prefix: | bmrc_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | instant

X
- Definition Period For Fixed Annual Retirement Benefit Payments + References No definition available. + Details
Name: | bmrc_PeriodForFixedAnnualRetirementBenefitPayments
Namespace Prefix: | bmrc_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount of asset (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 -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=123447040&loc=d3e1928-114920 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 45 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=123453770&loc=d3e1703-114919 + Details
Name: | us-gaap_DefinedBenefitPlanAmountsRecognizedInBalanceSheet
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

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
- Details
Name: | us-gaap_BusinessAcquisitionAxis=bmrc_BankOfNapaMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_BusinessAcquisitionAxis=bmrc_AmericanRiverBankARBMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

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: |