XML 57 R48.htm IDEA: XBRL DOCUMENT
v3.23.3

Loans and Allowance for Credit Losses on Loans - Schedule of Allocation of the Allowance for Credit Losses on Loans (Details) - USD ($) $ in Thousands | Sep. 30, 2023 | Jun. 30, 2023 | Dec. 31, 2022 | Sep. 30, 2022 | Jun. 30, 2022 | Dec. 31, 2021
--- | --- | --- | --- | --- | --- | ---
Financing Receivable, Troubled Debt Restructuring [Line Items] |  |  |  |  |  |
Allowance for credit losses | $ 24,260 | $ 23,832 | $ 22,983 | $ 22,963 | $ 22,539 | $ 23,023
Modeled expected credit losses |  |  |  |  |  |
Financing Receivable, Troubled Debt Restructuring [Line Items] |  |  |  |  |  |
Allowance for credit losses | 11,567 |  | 12,651 |  |  |
Qualitative adjustments |  |  |  |  |  |
Financing Receivable, Troubled Debt Restructuring [Line Items] |  |  |  |  |  |
Allowance for credit losses | 12,686 |  | 10,323 |  |  |
Specific allocations |  |  |  |  |  |
Financing Receivable, Troubled Debt Restructuring [Line Items] |  |  |  |  |  |
Allowance for credit losses | 7 |  | 9 |  |  |
Commercial loans | Commercial and industrial |  |  |  |  |  |
Financing Receivable, Troubled Debt Restructuring [Line Items] |  |  |  |  |  |
Allowance for credit losses | 1,808 | 1,831 | 1,794 | 1,958 | 1,699 | 1,709
Commercial loans | Commercial and industrial | Modeled expected credit losses |  |  |  |  |  |
Financing Receivable, Troubled Debt Restructuring [Line Items] |  |  |  |  |  |
Allowance for credit losses | 1,042 |  | 1,079 |  |  |
Commercial loans | Commercial and industrial | Qualitative adjustments |  |  |  |  |  |
Financing Receivable, Troubled Debt Restructuring [Line Items] |  |  |  |  |  |
Allowance for credit losses | 761 |  | 706 |  |  |
Commercial loans | Commercial and industrial | Specific allocations |  |  |  |  |  |
Financing Receivable, Troubled Debt Restructuring [Line Items] |  |  |  |  |  |
Allowance for credit losses | 5 |  | 9 |  |  |
Commercial real estate loans | Commercial owner-occupied |  |  |  |  |  |
Financing Receivable, Troubled Debt Restructuring [Line Items] |  |  |  |  |  |
Allowance for credit losses | 2,530 | 2,589 | 2,487 | 2,536 | 2,617 | 2,776
Commercial real estate loans | Commercial owner-occupied | Modeled expected credit losses |  |  |  |  |  |
Financing Receivable, Troubled Debt Restructuring [Line Items] |  |  |  |  |  |
Allowance for credit losses | 1,315 |  | 1,497 |  |  |
Commercial real estate loans | Commercial owner-occupied | Qualitative adjustments |  |  |  |  |  |
Financing Receivable, Troubled Debt Restructuring [Line Items] |  |  |  |  |  |
Allowance for credit losses | 1,214 |  | 990 |  |  |
Commercial real estate loans | Commercial owner-occupied | Specific allocations |  |  |  |  |  |
Financing Receivable, Troubled Debt Restructuring [Line Items] |  |  |  |  |  |
Allowance for credit losses | 1 |  | 0 |  |  |
Commercial real estate loans | Commercial non-owner occupied |  |  |  |  |  |
Financing Receivable, Troubled Debt Restructuring [Line Items] |  |  |  |  |  |
Allowance for credit losses | 13,624 | 13,201 | 12,676 | 12,738 | 12,439 |
Commercial real estate loans | Commercial non-owner occupied | Modeled expected credit losses |  |  |  |  |  |
Financing Receivable, Troubled Debt Restructuring [Line Items] |  |  |  |  |  |
Allowance for credit losses | 7,324 |  | 7,937 |  |  |
Commercial real estate loans | Commercial non-owner occupied | Qualitative adjustments |  |  |  |  |  |
Financing Receivable, Troubled Debt Restructuring [Line Items] |  |  |  |  |  |
Allowance for credit losses | 6,300 |  | 4,739 |  |  |
Commercial real estate loans | Commercial non-owner occupied | Specific allocations |  |  |  |  |  |
Financing Receivable, Troubled Debt Restructuring [Line Items] |  |  |  |  |  |
Allowance for credit losses | 0 |  | 0 |  |  |
Commercial real estate loans | Construction |  |  |  |  |  |
Financing Receivable, Troubled Debt Restructuring [Line Items] |  |  |  |  |  |
Allowance for credit losses | 2,018 | 1,942 | 1,937 | 1,784 | 1,737 | 1,653
Commercial real estate loans | Construction | Modeled expected credit losses |  |  |  |  |  |
Financing Receivable, Troubled Debt Restructuring [Line Items] |  |  |  |  |  |
Allowance for credit losses | 213 |  | 453 |  |  |
Commercial real estate loans | Construction | Qualitative adjustments |  |  |  |  |  |
Financing Receivable, Troubled Debt Restructuring [Line Items] |  |  |  |  |  |
Allowance for credit losses | 1,805 |  | 1,484 |  |  |
Commercial real estate loans | Construction | Specific allocations |  |  |  |  |  |
Financing Receivable, Troubled Debt Restructuring [Line Items] |  |  |  |  |  |
Allowance for credit losses | 0 |  | 0 |  |  |
Residential loans | Home equity |  |  |  |  |  |
Financing Receivable, Troubled Debt Restructuring [Line Items] |  |  |  |  |  |
Allowance for credit losses | 565 | 561 | 558 | 542 | 530 | 595
Residential loans | Home equity | Modeled expected credit losses |  |  |  |  |  |
Financing Receivable, Troubled Debt Restructuring [Line Items] |  |  |  |  |  |
Allowance for credit losses | 494 |  | 504 |  |  |
Residential loans | Home equity | Qualitative adjustments |  |  |  |  |  |
Financing Receivable, Troubled Debt Restructuring [Line Items] |  |  |  |  |  |
Allowance for credit losses | 71 |  | 54 |  |  |
Residential loans | Home equity | Specific allocations |  |  |  |  |  |
Financing Receivable, Troubled Debt Restructuring [Line Items] |  |  |  |  |  |
Allowance for credit losses | 0 |  | 0 |  |  |
Residential loans | Other residential |  |  |  |  |  |
Financing Receivable, Troubled Debt Restructuring [Line Items] |  |  |  |  |  |
Allowance for credit losses | 605 | 599 | 595 | 590 | 585 | 644
Residential loans | Other residential | Modeled expected credit losses |  |  |  |  |  |
Financing Receivable, Troubled Debt Restructuring [Line Items] |  |  |  |  |  |
Allowance for credit losses | 566 |  | 571 |  |  |
Residential loans | Other residential | Qualitative adjustments |  |  |  |  |  |
Financing Receivable, Troubled Debt Restructuring [Line Items] |  |  |  |  |  |
Allowance for credit losses | 38 |  | 24 |  |  |
Residential loans | Other residential | Specific allocations |  |  |  |  |  |
Financing Receivable, Troubled Debt Restructuring [Line Items] |  |  |  |  |  |
Allowance for credit losses | 1 |  | 0 |  |  |
Consumer loans | Installment and other consumer loans |  |  |  |  |  |
Financing Receivable, Troubled Debt Restructuring [Line Items] |  |  |  |  |  |
Allowance for credit losses | 951 | 940 | 868 | 815 | 733 | 621
Consumer loans | Installment and other consumer loans | Modeled expected credit losses |  |  |  |  |  |
Financing Receivable, Troubled Debt Restructuring [Line Items] |  |  |  |  |  |
Allowance for credit losses | 613 |  | 610 |  |  |
Consumer loans | Installment and other consumer loans | Qualitative adjustments |  |  |  |  |  |
Financing Receivable, Troubled Debt Restructuring [Line Items] |  |  |  |  |  |
Allowance for credit losses | 338 |  | 258 |  |  |
Consumer loans | Installment and other consumer loans | Specific allocations |  |  |  |  |  |
Financing Receivable, Troubled Debt Restructuring [Line Items] |  |  |  |  |  |
Allowance for credit losses | 0 |  | 0 |  |  |
Unallocated |  |  |  |  |  |
Financing Receivable, Troubled Debt Restructuring [Line Items] |  |  |  |  |  |
Allowance for credit losses | 2,159 | $ 2,169 | 2,068 | $ 2,000 | $ 2,199 | $ 2,286
Unallocated | Modeled expected credit losses |  |  |  |  |  |
Financing Receivable, Troubled Debt Restructuring [Line Items] |  |  |  |  |  |
Allowance for credit losses | 0 |  | 0 |  |  |
Unallocated | Qualitative adjustments |  |  |  |  |  |
Financing Receivable, Troubled Debt Restructuring [Line Items] |  |  |  |  |  |
Allowance for credit losses | 2,159 |  | 2,068 |  |  |
Unallocated | Specific allocations |  |  |  |  |  |
Financing Receivable, Troubled Debt Restructuring [Line Items] |  |  |  |  |  |
Allowance for credit losses | $ 0 |  | $ 0 |  |  |

X
- Definition Amount excluding accrued interest, of allowance for credit loss on financing receivable. Excludes net investment in lease. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 326 -SubTopic 20 -Name Accounting Standards Codification -Section 45 -Paragraph 1 -Publisher FASB -URI https://asc.fasb.org//1943274/2147479344/326-20-45-1 + Details
Name: | us-gaap_FinancingReceivableAllowanceForCreditLossExcludingAccruedInterest
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
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 Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 310 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 42 -Subparagraph (a)(1) -Publisher FASB -URI https://asc.fasb.org//1943274/2147481962/310-10-50-42 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Topic 310 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 42 -Subparagraph (a)(2) -Publisher FASB -URI https://asc.fasb.org//1943274/2147481962/310-10-50-42 Reference 3: http://www.xbrl.org/2003/role/exampleRef -Topic 310 -SubTopic 10 -Name Accounting Standards Codification -Section 55 -Paragraph 12A -Publisher FASB -URI https://asc.fasb.org//1943274/2147481933/310-10-55-12A Reference 4: http://www.xbrl.org/2003/role/disclosureRef -Topic 310 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 33 -Publisher FASB -URI https://asc.fasb.org//1943274/2147481962/310-10-50-33 Reference 5: http://www.xbrl.org/2003/role/disclosureRef -Topic 310 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 34 -Publisher FASB -URI https://asc.fasb.org//1943274/2147481962/310-10-50-34 + Details
Name: | us-gaap_FinancingReceivableModificationsLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | bmrc_AllowanceForCreditLossAllocationAxis=bmrc_ModeledExpectedCreditLossesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | bmrc_AllowanceForCreditLossAllocationAxis=bmrc_QualitativeAdjustmentsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | bmrc_AllowanceForCreditLossAllocationAxis=bmrc_SpecificAllocationsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

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

X
- Details
Name: | us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=bmrc_CommercialAndIndustrialMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

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

X
- Details
Name: | us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=bmrc_CommercialRealEstateLoanOwnerOccupiedMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=bmrc_CommercialRealEstateLoanNonOwnerOccupiedMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=us-gaap_ConstructionLoansMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

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

X
- Details
Name: | us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=us-gaap_HomeEquityLoanMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=bmrc_OtherResidentialLoanMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

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

X
- Details
Name: | us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=bmrc_InstallmentAndOtherConsumerMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

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