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Loans and Allowance for Loan Losses - Impaired Loans and Related Allowance (Details) (USD $) | 3 Months Ended | 12 Months Ended
--- | --- | ---
Mar. 31, 2015 | Mar. 31, 2014 | Dec. 31, 2014
Recorded investment in impaired loans: |  |  |
With no specific allowance recorded | $ 16,427,000 us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceRecordedInvestment |  | $ 16,464,000 us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceRecordedInvestment
With a specific allowance recorded | 8,683,000 us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceRecordedInvestment |  | 8,759,000 us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceRecordedInvestment
Total recorded investment in impaired loans | 25,110,000 us-gaap_ImpairedFinancingReceivableRecordedInvestment |  | 25,223,000 us-gaap_ImpairedFinancingReceivableRecordedInvestment
Unpaid principal balance of impaired loans: |  |  |
With no specific allowance recorded | 22,106,000 us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceUnpaidPrincipalBalance |  | 22,677,000 us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceUnpaidPrincipalBalance
With a specific allowance recorded | 8,939,000 us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceUnpaidPrincipalBalance |  | 9,028,000 us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceUnpaidPrincipalBalance
Total unpaid principal balance of impaired loans | 31,045,000 us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance |  | 31,705,000 us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance
Specific valuation | 961,000 us-gaap_ImpairedFinancingReceivableRelatedAllowance |  | 1,138,000 us-gaap_ImpairedFinancingReceivableRelatedAllowance
Average recorded investment in impaired loans during the period | 25,168,000 us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment | 25,751,000 us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment | 25,909,000 us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
Interest income recognized on impaired loans during the period ended | 190,000 us-gaap_ImpairedFinancingReceivableInterestIncomeAccrualMethod | 274,000 us-gaap_ImpairedFinancingReceivableInterestIncomeAccrualMethod | 948,000 us-gaap_ImpairedFinancingReceivableInterestIncomeAccrualMethod
Gross interest income that would have been recorded had nonaccrual loans been current | 231,000 us-gaap_LoansAndLeasesReceivableImpairedInterestLostOnNonaccrualLoans | 205,000 us-gaap_LoansAndLeasesReceivableImpairedInterestLostOnNonaccrualLoans |
Charged-off portion of impaired loans | 5,400,000 bmrc_FinancingReceivableImpairedLoansPortionOfLoansChargedOff |  |
Outstanding commitments to extend credit on impaired loans | 1,200,000 us-gaap_LoansAndLeasesReceivableImpairedCommitmentToLend |  |
Commercial and industrial |  |  |
Recorded investment in impaired loans: |  |  |
With no specific allowance recorded | 1,318,000 us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceRecordedInvestment / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialLoanMember |  | 1,141,000 us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceRecordedInvestment / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialLoanMember
With a specific allowance recorded | 2,533,000 us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceRecordedInvestment / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialLoanMember |  | 2,443,000 us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceRecordedInvestment / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialLoanMember
Total recorded investment in impaired loans | 3,851,000 us-gaap_ImpairedFinancingReceivableRecordedInvestment / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialLoanMember |  | 3,584,000 us-gaap_ImpairedFinancingReceivableRecordedInvestment / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialLoanMember
Unpaid principal balance of impaired loans: |  |  |
With no specific allowance recorded | 1,315,000 us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceUnpaidPrincipalBalance / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialLoanMember |  | 1,186,000 us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceUnpaidPrincipalBalance / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialLoanMember
With a specific allowance recorded | 2,604,000 us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceUnpaidPrincipalBalance / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialLoanMember |  | 2,524,000 us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceUnpaidPrincipalBalance / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialLoanMember
Total unpaid principal balance of impaired loans | 3,919,000 us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialLoanMember |  | 3,710,000 us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialLoanMember
Specific valuation | 652,000 us-gaap_ImpairedFinancingReceivableRelatedAllowance / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialLoanMember |  | 694,000 us-gaap_ImpairedFinancingReceivableRelatedAllowance / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialLoanMember
Average recorded investment in impaired loans during the period | 3,718,000 us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialLoanMember | 5,945,000 us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialLoanMember | 5,354,000 us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialLoanMember
Interest income recognized on impaired loans during the period ended | 62,000 us-gaap_ImpairedFinancingReceivableInterestIncomeAccrualMethod / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialLoanMember | 118,000 us-gaap_ImpairedFinancingReceivableInterestIncomeAccrualMethod / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialLoanMember | 378,000 us-gaap_ImpairedFinancingReceivableInterestIncomeAccrualMethod / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialLoanMember
Commercial real estate, owner-occupied |  |  |
Recorded investment in impaired loans: |  |  |
With no specific allowance recorded | 5,545,000 us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceRecordedInvestment / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = bmrc_CommercialRealEstateOwnerOccupiedFinancingReceivableMember |  | 5,577,000 us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceRecordedInvestment / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = bmrc_CommercialRealEstateOwnerOccupiedFinancingReceivableMember
With a specific allowance recorded | 2,882,000 us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceRecordedInvestment / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = bmrc_CommercialRealEstateOwnerOccupiedFinancingReceivableMember |  | 2,882,000 us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceRecordedInvestment / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = bmrc_CommercialRealEstateOwnerOccupiedFinancingReceivableMember
Total recorded investment in impaired loans | 8,427,000 us-gaap_ImpairedFinancingReceivableRecordedInvestment / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = bmrc_CommercialRealEstateOwnerOccupiedFinancingReceivableMember |  | 8,459,000 us-gaap_ImpairedFinancingReceivableRecordedInvestment / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = bmrc_CommercialRealEstateOwnerOccupiedFinancingReceivableMember
Unpaid principal balance of impaired loans: |  |  |
With no specific allowance recorded | 6,545,000 us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceUnpaidPrincipalBalance / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = bmrc_CommercialRealEstateOwnerOccupiedFinancingReceivableMember |  | 6,577,000 us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceUnpaidPrincipalBalance / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = bmrc_CommercialRealEstateOwnerOccupiedFinancingReceivableMember
With a specific allowance recorded | 2,882,000 us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceUnpaidPrincipalBalance / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = bmrc_CommercialRealEstateOwnerOccupiedFinancingReceivableMember |  | 2,882,000 us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceUnpaidPrincipalBalance / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = bmrc_CommercialRealEstateOwnerOccupiedFinancingReceivableMember
Total unpaid principal balance of impaired loans | 9,427,000 us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = bmrc_CommercialRealEstateOwnerOccupiedFinancingReceivableMember |  | 9,459,000 us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = bmrc_CommercialRealEstateOwnerOccupiedFinancingReceivableMember
Specific valuation | 32,000 us-gaap_ImpairedFinancingReceivableRelatedAllowance / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = bmrc_CommercialRealEstateOwnerOccupiedFinancingReceivableMember |  | 65,000 us-gaap_ImpairedFinancingReceivableRelatedAllowance / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = bmrc_CommercialRealEstateOwnerOccupiedFinancingReceivableMember
Average recorded investment in impaired loans during the period | 8,443,000 us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = bmrc_CommercialRealEstateOwnerOccupiedFinancingReceivableMember | 5,484,000 us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = bmrc_CommercialRealEstateOwnerOccupiedFinancingReceivableMember | 6,604,000 us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = bmrc_CommercialRealEstateOwnerOccupiedFinancingReceivableMember
Interest income recognized on impaired loans during the period ended | 66,000 us-gaap_ImpairedFinancingReceivableInterestIncomeAccrualMethod / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = bmrc_CommercialRealEstateOwnerOccupiedFinancingReceivableMember | 83,000 us-gaap_ImpairedFinancingReceivableInterestIncomeAccrualMethod / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = bmrc_CommercialRealEstateOwnerOccupiedFinancingReceivableMember | 288,000 us-gaap_ImpairedFinancingReceivableInterestIncomeAccrualMethod / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = bmrc_CommercialRealEstateOwnerOccupiedFinancingReceivableMember
Commercial real estate, investor |  |  |
Recorded investment in impaired loans: |  |  |
With no specific allowance recorded | 2,875,000 us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceRecordedInvestment / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = bmrc_CommercialRealEstateInvestorFinancingReceivableMember |  | 2,954,000 us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceRecordedInvestment / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = bmrc_CommercialRealEstateInvestorFinancingReceivableMember
With a specific allowance recorded | 0 us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceRecordedInvestment / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = bmrc_CommercialRealEstateInvestorFinancingReceivableMember |  | 0 us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceRecordedInvestment / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = bmrc_CommercialRealEstateInvestorFinancingReceivableMember
Total recorded investment in impaired loans | 2,875,000 us-gaap_ImpairedFinancingReceivableRecordedInvestment / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = bmrc_CommercialRealEstateInvestorFinancingReceivableMember |  | 2,954,000 us-gaap_ImpairedFinancingReceivableRecordedInvestment / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = bmrc_CommercialRealEstateInvestorFinancingReceivableMember
Unpaid principal balance of impaired loans: |  |  |
With no specific allowance recorded | 4,867,000 us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceUnpaidPrincipalBalance / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = bmrc_CommercialRealEstateInvestorFinancingReceivableMember |  | 4,945,000 us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceUnpaidPrincipalBalance / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = bmrc_CommercialRealEstateInvestorFinancingReceivableMember
With a specific allowance recorded | 0 us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceUnpaidPrincipalBalance / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = bmrc_CommercialRealEstateInvestorFinancingReceivableMember |  | 0 us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceUnpaidPrincipalBalance / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = bmrc_CommercialRealEstateInvestorFinancingReceivableMember
Total unpaid principal balance of impaired loans | 4,867,000 us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = bmrc_CommercialRealEstateInvestorFinancingReceivableMember |  | 4,945,000 us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = bmrc_CommercialRealEstateInvestorFinancingReceivableMember
Specific valuation | 0 us-gaap_ImpairedFinancingReceivableRelatedAllowance / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = bmrc_CommercialRealEstateInvestorFinancingReceivableMember |  | 0 us-gaap_ImpairedFinancingReceivableRelatedAllowance / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = bmrc_CommercialRealEstateInvestorFinancingReceivableMember
Average recorded investment in impaired loans during the period | 2,915,000 us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = bmrc_CommercialRealEstateInvestorFinancingReceivableMember | 3,283,000 us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = bmrc_CommercialRealEstateInvestorFinancingReceivableMember | 3,138,000 us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = bmrc_CommercialRealEstateInvestorFinancingReceivableMember
Interest income recognized on impaired loans during the period ended | 6,000 us-gaap_ImpairedFinancingReceivableInterestIncomeAccrualMethod / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = bmrc_CommercialRealEstateInvestorFinancingReceivableMember | 7,000 us-gaap_ImpairedFinancingReceivableInterestIncomeAccrualMethod / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = bmrc_CommercialRealEstateInvestorFinancingReceivableMember | 28,000 us-gaap_ImpairedFinancingReceivableInterestIncomeAccrualMethod / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = bmrc_CommercialRealEstateInvestorFinancingReceivableMember
Construction |  |  |
Recorded investment in impaired loans: |  |  |
With no specific allowance recorded | 5,107,000 us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceRecordedInvestment / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ConstructionLoansMember |  | 5,134,000 us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceRecordedInvestment / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ConstructionLoansMember
With a specific allowance recorded | 560,000 us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceRecordedInvestment / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ConstructionLoansMember |  | 561,000 us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceRecordedInvestment / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ConstructionLoansMember
Total recorded investment in impaired loans | 5,667,000 us-gaap_ImpairedFinancingReceivableRecordedInvestment / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ConstructionLoansMember |  | 5,695,000 us-gaap_ImpairedFinancingReceivableRecordedInvestment / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ConstructionLoansMember
Unpaid principal balance of impaired loans: |  |  |
With no specific allowance recorded | 7,797,000 us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceUnpaidPrincipalBalance / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ConstructionLoansMember |  | 7,824,000 us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceUnpaidPrincipalBalance / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ConstructionLoansMember
With a specific allowance recorded | 745,000 us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceUnpaidPrincipalBalance / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ConstructionLoansMember |  | 749,000 us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceUnpaidPrincipalBalance / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ConstructionLoansMember
Total unpaid principal balance of impaired loans | 8,542,000 us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ConstructionLoansMember |  | 8,573,000 us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ConstructionLoansMember
Specific valuation | 3,000 us-gaap_ImpairedFinancingReceivableRelatedAllowance / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ConstructionLoansMember |  | 3,000 us-gaap_ImpairedFinancingReceivableRelatedAllowance / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ConstructionLoansMember
Average recorded investment in impaired loans during the period | 5,681,000 us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ConstructionLoansMember | 6,524,000 us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ConstructionLoansMember | 6,471,000 us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ConstructionLoansMember
Interest income recognized on impaired loans during the period ended | 9,000 us-gaap_ImpairedFinancingReceivableInterestIncomeAccrualMethod / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ConstructionLoansMember | 21,000 us-gaap_ImpairedFinancingReceivableInterestIncomeAccrualMethod / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ConstructionLoansMember | 85,000 us-gaap_ImpairedFinancingReceivableInterestIncomeAccrualMethod / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ConstructionLoansMember
Home equity |  |  |
Recorded investment in impaired loans: |  |  |
With no specific allowance recorded | 263,000 us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceRecordedInvestment / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_HomeEquityMember |  | 393,000 us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceRecordedInvestment / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_HomeEquityMember
With a specific allowance recorded | 298,000 us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceRecordedInvestment / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_HomeEquityMember |  | 300,000 us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceRecordedInvestment / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_HomeEquityMember
Total recorded investment in impaired loans | 561,000 us-gaap_ImpairedFinancingReceivableRecordedInvestment / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_HomeEquityMember |  | 693,000 us-gaap_ImpairedFinancingReceivableRecordedInvestment / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_HomeEquityMember
Unpaid principal balance of impaired loans: |  |  |
With no specific allowance recorded | 263,000 us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceUnpaidPrincipalBalance / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_HomeEquityMember |  | 880,000 us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceUnpaidPrincipalBalance / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_HomeEquityMember
With a specific allowance recorded | 298,000 us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceUnpaidPrincipalBalance / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_HomeEquityMember |  | 300,000 us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceUnpaidPrincipalBalance / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_HomeEquityMember
Total unpaid principal balance of impaired loans | 561,000 us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_HomeEquityMember |  | 1,180,000 us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_HomeEquityMember
Specific valuation | 1,000 us-gaap_ImpairedFinancingReceivableRelatedAllowance / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_HomeEquityMember |  | 0 us-gaap_ImpairedFinancingReceivableRelatedAllowance / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_HomeEquityMember
Average recorded investment in impaired loans during the period | 627,000 us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_HomeEquityMember | 577,000 us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_HomeEquityMember | 741,000 us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_HomeEquityMember
Interest income recognized on impaired loans during the period ended | 5,000 us-gaap_ImpairedFinancingReceivableInterestIncomeAccrualMethod / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_HomeEquityMember | 4,000 us-gaap_ImpairedFinancingReceivableInterestIncomeAccrualMethod / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_HomeEquityMember | 19,000 us-gaap_ImpairedFinancingReceivableInterestIncomeAccrualMethod / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_HomeEquityMember
Other residential |  |  |
Recorded investment in impaired loans: |  |  |
With no specific allowance recorded | 1,024,000 us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceRecordedInvestment / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = bmrc_OtherResidentialFinancingReceivableMember |  | 1,026,000 us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceRecordedInvestment / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = bmrc_OtherResidentialFinancingReceivableMember
With a specific allowance recorded | 1,012,000 us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceRecordedInvestment / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = bmrc_OtherResidentialFinancingReceivableMember |  | 1,019,000 us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceRecordedInvestment / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = bmrc_OtherResidentialFinancingReceivableMember
Total recorded investment in impaired loans | 2,036,000 us-gaap_ImpairedFinancingReceivableRecordedInvestment / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = bmrc_OtherResidentialFinancingReceivableMember |  | 2,045,000 us-gaap_ImpairedFinancingReceivableRecordedInvestment / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = bmrc_OtherResidentialFinancingReceivableMember
Unpaid principal balance of impaired loans: |  |  |
With no specific allowance recorded | 1,024,000 us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceUnpaidPrincipalBalance / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = bmrc_OtherResidentialFinancingReceivableMember |  | 1,026,000 us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceUnpaidPrincipalBalance / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = bmrc_OtherResidentialFinancingReceivableMember
With a specific allowance recorded | 1,012,000 us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceUnpaidPrincipalBalance / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = bmrc_OtherResidentialFinancingReceivableMember |  | 1,019,000 us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceUnpaidPrincipalBalance / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = bmrc_OtherResidentialFinancingReceivableMember
Total unpaid principal balance of impaired loans | 2,036,000 us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = bmrc_OtherResidentialFinancingReceivableMember |  | 2,045,000 us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = bmrc_OtherResidentialFinancingReceivableMember
Specific valuation | 85,000 us-gaap_ImpairedFinancingReceivableRelatedAllowance / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = bmrc_OtherResidentialFinancingReceivableMember |  | 92,000 us-gaap_ImpairedFinancingReceivableRelatedAllowance / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = bmrc_OtherResidentialFinancingReceivableMember
Average recorded investment in impaired loans during the period | 2,041,000 us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = bmrc_OtherResidentialFinancingReceivableMember | 2,054,000 us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = bmrc_OtherResidentialFinancingReceivableMember | 1,744,000 us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = bmrc_OtherResidentialFinancingReceivableMember
Interest income recognized on impaired loans during the period ended | 23,000 us-gaap_ImpairedFinancingReceivableInterestIncomeAccrualMethod / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = bmrc_OtherResidentialFinancingReceivableMember | 23,000 us-gaap_ImpairedFinancingReceivableInterestIncomeAccrualMethod / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = bmrc_OtherResidentialFinancingReceivableMember | 74,000 us-gaap_ImpairedFinancingReceivableInterestIncomeAccrualMethod / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = bmrc_OtherResidentialFinancingReceivableMember
Installment and other consumer |  |  |
Recorded investment in impaired loans: |  |  |
With no specific allowance recorded | 295,000 us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceRecordedInvestment / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ConsumerPortfolioSegmentMember |  | 239,000 us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceRecordedInvestment / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ConsumerPortfolioSegmentMember
With a specific allowance recorded | 1,398,000 us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceRecordedInvestment / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ConsumerPortfolioSegmentMember |  | 1,554,000 us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceRecordedInvestment / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ConsumerPortfolioSegmentMember
Total recorded investment in impaired loans | 1,693,000 us-gaap_ImpairedFinancingReceivableRecordedInvestment / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ConsumerPortfolioSegmentMember |  | 1,793,000 us-gaap_ImpairedFinancingReceivableRecordedInvestment / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ConsumerPortfolioSegmentMember
Unpaid principal balance of impaired loans: |  |  |
With no specific allowance recorded | 295,000 us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceUnpaidPrincipalBalance / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ConsumerPortfolioSegmentMember |  | 239,000 us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceUnpaidPrincipalBalance / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ConsumerPortfolioSegmentMember
With a specific allowance recorded | 1,398,000 us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceUnpaidPrincipalBalance / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ConsumerPortfolioSegmentMember |  | 1,554,000 us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceUnpaidPrincipalBalance / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ConsumerPortfolioSegmentMember
Total unpaid principal balance of impaired loans | 1,693,000 us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ConsumerPortfolioSegmentMember |  | 1,793,000 us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ConsumerPortfolioSegmentMember
Specific valuation | 188,000 us-gaap_ImpairedFinancingReceivableRelatedAllowance / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ConsumerPortfolioSegmentMember |  | 284,000 us-gaap_ImpairedFinancingReceivableRelatedAllowance / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ConsumerPortfolioSegmentMember
Average recorded investment in impaired loans during the period | 1,743,000 us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ConsumerPortfolioSegmentMember | 1,884,000 us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ConsumerPortfolioSegmentMember | 1,857,000 us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ConsumerPortfolioSegmentMember
Interest income recognized on impaired loans during the period ended | $ 19,000 us-gaap_ImpairedFinancingReceivableInterestIncomeAccrualMethod / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ConsumerPortfolioSegmentMember | $ 18,000 us-gaap_ImpairedFinancingReceivableInterestIncomeAccrualMethod / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ConsumerPortfolioSegmentMember | $ 76,000 us-gaap_ImpairedFinancingReceivableInterestIncomeAccrualMethod / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ConsumerPortfolioSegmentMember

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- Definition Average amount of investment of impaired financing receivables with related allowance for credit losses and without a related allowance for credit losses. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 17 -URI http://asc.fasb.org/extlink&oid=49124121&loc=d3e5258-111524 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 15 -Subparagraph (c)(1) -URI http://asc.fasb.org/extlink&oid=49124121&loc=d3e5212-111524 + Details
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