XML 44 R35.htm IDEA: XBRL DOCUMENT
v3.22.2

Investment Securities - Available-for-Sale Securities Amortized Cost and Fair Value (Details) - USD ($) | Jun. 30, 2022 | Dec. 31, 2021
--- | --- | ---
Debt Securities, Available-for-sale [Line Items] |  |
Available-for-sale, amortized cost | $ 960,379,000 | $ 1,169,520,000
Available-for-sale, gross unrealized gains | 80,000 | 11,074,000
Available-for-sale, gross unrealized losses | (67,310,000) | (13,026,000)
Allowance for Credit Losses | 0 | 0
Available-for-sale securities | 893,149,000 | 1,167,568,000
Accrued interest | 3,400,000 | 3,700,000
MBS pass-through securities issued by FHLMC, FNMA and GNMA |  |
Debt Securities, Available-for-sale [Line Items] |  |
Available-for-sale, amortized cost | 127,526,000 | 316,090,000
Available-for-sale, gross unrealized gains | 23,000 | 1,224,000
Available-for-sale, gross unrealized losses | (8,784,000) | (2,784,000)
Allowance for Credit Losses | 0 | 0
Available-for-sale securities | 118,765,000 | 314,530,000
CMOs issued by FHLMC |  |
Debt Securities, Available-for-sale [Line Items] |  |
Available-for-sale, amortized cost | 370,610,000 | 343,047,000
Available-for-sale, gross unrealized gains | 1,000 | 3,209,000
Available-for-sale, gross unrealized losses | (23,017,000) | (4,829,000)
Allowance for Credit Losses | 0 | 0
Available-for-sale securities | 347,594,000 | 341,427,000
CMOs issued by FNMA |  |
Debt Securities, Available-for-sale [Line Items] |  |
Available-for-sale, amortized cost | 40,375,000 | 48,187,000
Available-for-sale, gross unrealized gains | 1,000 | 152,000
Available-for-sale, gross unrealized losses | (2,960,000) | (611,000)
Allowance for Credit Losses | 0 | 0
Available-for-sale securities | 37,416,000 | 47,728,000
CMOs issued by GNMA |  |
Debt Securities, Available-for-sale [Line Items] |  |
Available-for-sale, amortized cost | 38,629,000 | 56,345,000
Available-for-sale, gross unrealized gains | 1,000 | 99,000
Available-for-sale, gross unrealized losses | (2,414,000) | (553,000)
Allowance for Credit Losses | 0 | 0
Available-for-sale securities | 36,216,000 | 55,891,000
SBA-backed securities |  |
Debt Securities, Available-for-sale [Line Items] |  |
Available-for-sale, amortized cost | 55,297,000 | 32,640,000
Available-for-sale, gross unrealized gains | 4,000 | 993,000
Available-for-sale, gross unrealized losses | (2,133,000) | (155,000)
Allowance for Credit Losses | 0 | 0
Available-for-sale securities | 53,168,000 | 33,478,000
Debentures of government- sponsored agencies |  |
Debt Securities, Available-for-sale [Line Items] |  |
Available-for-sale, amortized cost | 149,099,000 | 191,449,000
Available-for-sale, gross unrealized gains | 0 | 25,000
Available-for-sale, gross unrealized losses | (9,759,000) | (2,947,000)
Allowance for Credit Losses | 0 | 0
Available-for-sale securities | 139,340,000 | 188,527,000
U.S. Treasury securities |  |
Debt Securities, Available-for-sale [Line Items] |  |
Available-for-sale, amortized cost | 11,895,000 | 11,886,000
Available-for-sale, gross unrealized gains | 0 | 0
Available-for-sale, gross unrealized losses | (1,251,000) | (256,000)
Allowance for Credit Losses | 0 |
Available-for-sale securities | 10,644,000 | 11,630,000
Obligations of state and political subdivisions |  |
Debt Securities, Available-for-sale [Line Items] |  |
Available-for-sale, amortized cost | 128,238,000 | 129,009,000
Available-for-sale, gross unrealized gains | 50,000 | 5,372,000
Available-for-sale, gross unrealized losses | (14,025,000) | (381,000)
Allowance for Credit Losses | 0 | 0
Available-for-sale securities | 114,263,000 | 134,000,000
Corporate bonds |  |
Debt Securities, Available-for-sale [Line Items] |  |
Available-for-sale, amortized cost | 36,989,000 | 39,001,000
Available-for-sale, gross unrealized gains | 0 | 0
Available-for-sale, gross unrealized losses | (2,897,000) | (506,000)
Allowance for Credit Losses | 0 | 0
Available-for-sale securities | 34,092,000 | 38,495,000
Asset-backed securities |  |
Debt Securities, Available-for-sale [Line Items] |  |
Available-for-sale, amortized cost | 1,721,000 | 1,866,000
Available-for-sale, gross unrealized gains | 0 | 0
Available-for-sale, gross unrealized losses | (70,000) | (4,000)
Allowance for Credit Losses | 0 | 0
Available-for-sale securities | $ 1,651,000 | $ 1,862,000

X
- Definition Amount, before tax, of unrealized gain in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale). + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (b) -URI https://asc.fasb.org/extlink&oid=126970911&loc=d3e27161-111563 + Details
Name: | us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Amount, before tax, of unrealized loss in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale). + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c) -URI https://asc.fasb.org/extlink&oid=126970911&loc=d3e27161-111563 + Details
Name: | us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount, after allowance for credit loss, of accrued interest on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale). + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 30 -Section 45 -Paragraph 1 -URI https://asc.fasb.org/extlink&oid=124258926&loc=SL82898722-210454 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 30 -Section 50 -Paragraph 3A -URI https://asc.fasb.org/extlink&oid=124269663&loc=SL120267853-210455 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 2A -URI https://asc.fasb.org/extlink&oid=126970911&loc=SL121698322-111563 Reference 4: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 30 -Section 50 -Paragraph 3B -URI https://asc.fasb.org/extlink&oid=124269663&loc=SL120267856-210455 + Details
Name: | us-gaap_DebtSecuritiesAvailableForSaleAccruedInterestAfterAllowanceForCreditLoss
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount excluding accrued interest, of allowance for credit loss on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale). + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 30 -Section 45 -Paragraph 1 -URI https://asc.fasb.org/extlink&oid=124258926&loc=SL82898722-210454 + Details
Name: | us-gaap_DebtSecuritiesAvailableForSaleAmortizedCostAllowanceForCreditLossExcludingAccruedInterest
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Amortized cost excluding accrued interest, before allowance for credit loss, of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale). + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 30 -Section 45 -Paragraph 1 -URI https://asc.fasb.org/extlink&oid=124258926&loc=SL82898722-210454 + Details
Name: | us-gaap_DebtSecuritiesAvailableForSaleAmortizedCostExcludingAccruedInterestBeforeAllowanceForCreditLoss
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount excluding accrued interest, of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale). + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 30 -Section 45 -Paragraph 1 -URI https://asc.fasb.org/extlink&oid=124258926&loc=SL82898722-210454 + Details
Name: | us-gaap_DebtSecuritiesAvailableForSaleExcludingAccruedInterest
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_ScheduleOfAvailableForSaleSecuritiesLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | us-gaap_FinancialInstrumentAxis=us-gaap_MortgageBackedSecuritiesIssuedByUSGovernmentSponsoredEnterprisesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancialInstrumentAxis=us-gaap_FederalHomeLoanMortgageCorporationCertificatesAndObligationsFHLMCMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancialInstrumentAxis=us-gaap_FederalNationalMortgageAssociationCertificatesAndObligationsFNMAMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancialInstrumentAxis=us-gaap_GovernmentNationalMortgageAssociationCertificatesAndObligationsGNMAMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancialInstrumentAxis=bmrc_SmallBusinessAdministrationSBABackedSecuritiesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancialInstrumentAxis=us-gaap_USGovernmentSponsoredEnterprisesDebtSecuritiesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancialInstrumentAxis=us-gaap_USTreasurySecuritiesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancialInstrumentAxis=us-gaap_USStatesAndPoliticalSubdivisionsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancialInstrumentAxis=us-gaap_CorporateBondSecuritiesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancialInstrumentAxis=us-gaap_AssetBackedSecuritiesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |