XML 36 R35.htm IDEA: XBRL DOCUMENT
v2.4.1.9

Loans and Allowance for Loan Losses - Credit Quality of Loans (Details) (USD $) In Thousands, unless otherwise specified | Mar. 31, 2015 | Dec. 31, 2014
--- | --- | ---
Financing Receivable, Recorded Investment [Line Items] |  |  |  |
Total loans | $ 1,346,484 us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome | [1] | $ 1,363,351 us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome | [1]
Receivables Acquired with Deteriorated Credit Quality |  |  |  |
Financing Receivable, Recorded Investment [Line Items] |  |  |  |
Purchase credit-impaired | 5,072 us-gaap_NotesReceivableNet / us-gaap_ReceivablesAcquiredWithDeterioratedCreditQualityAxis = us-gaap_ReceivablesAcquiredWithDeterioratedCreditQualityMember |  | 5,192 us-gaap_NotesReceivableNet / us-gaap_ReceivablesAcquiredWithDeterioratedCreditQualityAxis = us-gaap_ReceivablesAcquiredWithDeterioratedCreditQualityMember |
Pass |  |  |  |
Financing Receivable, Recorded Investment [Line Items] |  |  |  |
Total loans | 1,286,367 us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome / us-gaap_InternalCreditAssessmentAxis = us-gaap_PassMember |  | 1,293,968 us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome / us-gaap_InternalCreditAssessmentAxis = us-gaap_PassMember |
Pass | Receivables Acquired with Deteriorated Credit Quality |  |  |  |
Financing Receivable, Recorded Investment [Line Items] |  |  |  |
Purchase credit-impaired | 2,202 us-gaap_NotesReceivableNet / us-gaap_InternalCreditAssessmentAxis = us-gaap_PassMember / us-gaap_ReceivablesAcquiredWithDeterioratedCreditQualityAxis = us-gaap_ReceivablesAcquiredWithDeterioratedCreditQualityMember |  | 2,210 us-gaap_NotesReceivableNet / us-gaap_InternalCreditAssessmentAxis = us-gaap_PassMember / us-gaap_ReceivablesAcquiredWithDeterioratedCreditQualityAxis = us-gaap_ReceivablesAcquiredWithDeterioratedCreditQualityMember |
Special Mention |  |  |  |
Financing Receivable, Recorded Investment [Line Items] |  |  |  |
Total loans | 25,988 us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome / us-gaap_InternalCreditAssessmentAxis = us-gaap_SpecialMentionMember |  | 33,146 us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome / us-gaap_InternalCreditAssessmentAxis = us-gaap_SpecialMentionMember |
Special Mention | Receivables Acquired with Deteriorated Credit Quality |  |  |  |
Financing Receivable, Recorded Investment [Line Items] |  |  |  |
Purchase credit-impaired | 1,031 us-gaap_NotesReceivableNet / us-gaap_InternalCreditAssessmentAxis = us-gaap_SpecialMentionMember / us-gaap_ReceivablesAcquiredWithDeterioratedCreditQualityAxis = us-gaap_ReceivablesAcquiredWithDeterioratedCreditQualityMember |  | 1,140 us-gaap_NotesReceivableNet / us-gaap_InternalCreditAssessmentAxis = us-gaap_SpecialMentionMember / us-gaap_ReceivablesAcquiredWithDeterioratedCreditQualityAxis = us-gaap_ReceivablesAcquiredWithDeterioratedCreditQualityMember |
Substandard |  |  |  |
Financing Receivable, Recorded Investment [Line Items] |  |  |  |
Total loans | 34,129 us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome / us-gaap_InternalCreditAssessmentAxis = us-gaap_SubstandardMember |  | 36,237 us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome / us-gaap_InternalCreditAssessmentAxis = us-gaap_SubstandardMember |
Substandard | Receivables Acquired with Deteriorated Credit Quality |  |  |  |
Financing Receivable, Recorded Investment [Line Items] |  |  |  |
Purchase credit-impaired | 1,839 us-gaap_NotesReceivableNet / us-gaap_InternalCreditAssessmentAxis = us-gaap_SubstandardMember / us-gaap_ReceivablesAcquiredWithDeterioratedCreditQualityAxis = us-gaap_ReceivablesAcquiredWithDeterioratedCreditQualityMember |  | 1,842 us-gaap_NotesReceivableNet / us-gaap_InternalCreditAssessmentAxis = us-gaap_SubstandardMember / us-gaap_ReceivablesAcquiredWithDeterioratedCreditQualityAxis = us-gaap_ReceivablesAcquiredWithDeterioratedCreditQualityMember |
Commercial and industrial |  |  |  |
Financing Receivable, Recorded Investment [Line Items] |  |  |  |
Loans excluding purchased credit-impaired loans | 196,240 bmrc_LoansAndLeasesReceivableNetOfDeferredIncomeExcludingPurchasedCreditImpairedLoans / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialLoanMember |  | 209,899 bmrc_LoansAndLeasesReceivableNetOfDeferredIncomeExcludingPurchasedCreditImpairedLoans / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialLoanMember |
Total loans | 196,442 us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialLoanMember | [1] | 210,223 us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialLoanMember | [1]
Commercial and industrial | Receivables Acquired with Deteriorated Credit Quality |  |  |  |
Financing Receivable, Recorded Investment [Line Items] |  |  |  |
Purchase credit-impaired | 202 us-gaap_NotesReceivableNet / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialLoanMember / us-gaap_ReceivablesAcquiredWithDeterioratedCreditQualityAxis = us-gaap_ReceivablesAcquiredWithDeterioratedCreditQualityMember |  | 324 us-gaap_NotesReceivableNet / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialLoanMember / us-gaap_ReceivablesAcquiredWithDeterioratedCreditQualityAxis = us-gaap_ReceivablesAcquiredWithDeterioratedCreditQualityMember |
Commercial and industrial | Pass |  |  |  |
Financing Receivable, Recorded Investment [Line Items] |  |  |  |
Loans excluding purchased credit-impaired loans | 181,842 bmrc_LoansAndLeasesReceivableNetOfDeferredIncomeExcludingPurchasedCreditImpairedLoans / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialLoanMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_PassMember |  | 197,659 bmrc_LoansAndLeasesReceivableNetOfDeferredIncomeExcludingPurchasedCreditImpairedLoans / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialLoanMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_PassMember |
Commercial and industrial | Special Mention |  |  |  |
Financing Receivable, Recorded Investment [Line Items] |  |  |  |
Loans excluding purchased credit-impaired loans | 9,424 bmrc_LoansAndLeasesReceivableNetOfDeferredIncomeExcludingPurchasedCreditImpairedLoans / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialLoanMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_SpecialMentionMember |  | 6,776 bmrc_LoansAndLeasesReceivableNetOfDeferredIncomeExcludingPurchasedCreditImpairedLoans / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialLoanMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_SpecialMentionMember |
Commercial and industrial | Substandard |  |  |  |
Financing Receivable, Recorded Investment [Line Items] |  |  |  |
Loans excluding purchased credit-impaired loans | 4,974 bmrc_LoansAndLeasesReceivableNetOfDeferredIncomeExcludingPurchasedCreditImpairedLoans / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialLoanMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_SubstandardMember |  | 5,464 bmrc_LoansAndLeasesReceivableNetOfDeferredIncomeExcludingPurchasedCreditImpairedLoans / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialLoanMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_SubstandardMember |
Commercial real estate, owner-occupied |  |  |  |
Financing Receivable, Recorded Investment [Line Items] |  |  |  |
Loans excluding purchased credit-impaired loans | 232,708 bmrc_LoansAndLeasesReceivableNetOfDeferredIncomeExcludingPurchasedCreditImpairedLoans / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = bmrc_CommercialRealEstateOwnerOccupiedFinancingReceivableMember |  | 227,989 bmrc_LoansAndLeasesReceivableNetOfDeferredIncomeExcludingPurchasedCreditImpairedLoans / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = bmrc_CommercialRealEstateOwnerOccupiedFinancingReceivableMember |
Total loans | 235,337 us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = bmrc_CommercialRealEstateOwnerOccupiedFinancingReceivableMember | [1] | 230,605 us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = bmrc_CommercialRealEstateOwnerOccupiedFinancingReceivableMember | [1]
Commercial real estate, owner-occupied | Receivables Acquired with Deteriorated Credit Quality |  |  |  |
Financing Receivable, Recorded Investment [Line Items] |  |  |  |
Purchase credit-impaired | 2,629 us-gaap_NotesReceivableNet / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = bmrc_CommercialRealEstateOwnerOccupiedFinancingReceivableMember / us-gaap_ReceivablesAcquiredWithDeterioratedCreditQualityAxis = us-gaap_ReceivablesAcquiredWithDeterioratedCreditQualityMember |  | 2,616 us-gaap_NotesReceivableNet / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = bmrc_CommercialRealEstateOwnerOccupiedFinancingReceivableMember / us-gaap_ReceivablesAcquiredWithDeterioratedCreditQualityAxis = us-gaap_ReceivablesAcquiredWithDeterioratedCreditQualityMember |
Commercial real estate, owner-occupied | Pass |  |  |  |
Financing Receivable, Recorded Investment [Line Items] |  |  |  |
Loans excluding purchased credit-impaired loans | 211,551 bmrc_LoansAndLeasesReceivableNetOfDeferredIncomeExcludingPurchasedCreditImpairedLoans / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = bmrc_CommercialRealEstateOwnerOccupiedFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_PassMember |  | 205,820 bmrc_LoansAndLeasesReceivableNetOfDeferredIncomeExcludingPurchasedCreditImpairedLoans / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = bmrc_CommercialRealEstateOwnerOccupiedFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_PassMember |
Commercial real estate, owner-occupied | Special Mention |  |  |  |
Financing Receivable, Recorded Investment [Line Items] |  |  |  |
Loans excluding purchased credit-impaired loans | 10,281 bmrc_LoansAndLeasesReceivableNetOfDeferredIncomeExcludingPurchasedCreditImpairedLoans / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = bmrc_CommercialRealEstateOwnerOccupiedFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_SpecialMentionMember |  | 10,406 bmrc_LoansAndLeasesReceivableNetOfDeferredIncomeExcludingPurchasedCreditImpairedLoans / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = bmrc_CommercialRealEstateOwnerOccupiedFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_SpecialMentionMember |
Commercial real estate, owner-occupied | Substandard |  |  |  |
Financing Receivable, Recorded Investment [Line Items] |  |  |  |
Loans excluding purchased credit-impaired loans | 10,876 bmrc_LoansAndLeasesReceivableNetOfDeferredIncomeExcludingPurchasedCreditImpairedLoans / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = bmrc_CommercialRealEstateOwnerOccupiedFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_SubstandardMember |  | 11,763 bmrc_LoansAndLeasesReceivableNetOfDeferredIncomeExcludingPurchasedCreditImpairedLoans / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = bmrc_CommercialRealEstateOwnerOccupiedFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_SubstandardMember |
Commercial real estate, investor |  |  |  |
Financing Receivable, Recorded Investment [Line Items] |  |  |  |
Loans excluding purchased credit-impaired loans | 651,684 bmrc_LoansAndLeasesReceivableNetOfDeferredIncomeExcludingPurchasedCreditImpairedLoans / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = bmrc_CommercialRealEstateInvestorFinancingReceivableMember |  | 671,325 bmrc_LoansAndLeasesReceivableNetOfDeferredIncomeExcludingPurchasedCreditImpairedLoans / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = bmrc_CommercialRealEstateInvestorFinancingReceivableMember |
Total loans | 653,848 us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = bmrc_CommercialRealEstateInvestorFinancingReceivableMember | [1] | 673,499 us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = bmrc_CommercialRealEstateInvestorFinancingReceivableMember | [1]
Commercial real estate, investor | Receivables Acquired with Deteriorated Credit Quality |  |  |  |
Financing Receivable, Recorded Investment [Line Items] |  |  |  |
Purchase credit-impaired | 2,164 us-gaap_NotesReceivableNet / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = bmrc_CommercialRealEstateInvestorFinancingReceivableMember / us-gaap_ReceivablesAcquiredWithDeterioratedCreditQualityAxis = us-gaap_ReceivablesAcquiredWithDeterioratedCreditQualityMember |  | 2,174 us-gaap_NotesReceivableNet / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = bmrc_CommercialRealEstateInvestorFinancingReceivableMember / us-gaap_ReceivablesAcquiredWithDeterioratedCreditQualityAxis = us-gaap_ReceivablesAcquiredWithDeterioratedCreditQualityMember |
Commercial real estate, investor | Pass |  |  |  |
Financing Receivable, Recorded Investment [Line Items] |  |  |  |
Loans excluding purchased credit-impaired loans | 640,656 bmrc_LoansAndLeasesReceivableNetOfDeferredIncomeExcludingPurchasedCreditImpairedLoans / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = bmrc_CommercialRealEstateInvestorFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_PassMember |  | 651,548 bmrc_LoansAndLeasesReceivableNetOfDeferredIncomeExcludingPurchasedCreditImpairedLoans / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = bmrc_CommercialRealEstateInvestorFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_PassMember |
Commercial real estate, investor | Special Mention |  |  |  |
Financing Receivable, Recorded Investment [Line Items] |  |  |  |
Loans excluding purchased credit-impaired loans | 3,853 bmrc_LoansAndLeasesReceivableNetOfDeferredIncomeExcludingPurchasedCreditImpairedLoans / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = bmrc_CommercialRealEstateInvestorFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_SpecialMentionMember |  | 13,304 bmrc_LoansAndLeasesReceivableNetOfDeferredIncomeExcludingPurchasedCreditImpairedLoans / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = bmrc_CommercialRealEstateInvestorFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_SpecialMentionMember |
Commercial real estate, investor | Substandard |  |  |  |
Financing Receivable, Recorded Investment [Line Items] |  |  |  |
Loans excluding purchased credit-impaired loans | 7,175 bmrc_LoansAndLeasesReceivableNetOfDeferredIncomeExcludingPurchasedCreditImpairedLoans / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = bmrc_CommercialRealEstateInvestorFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_SubstandardMember |  | 6,473 bmrc_LoansAndLeasesReceivableNetOfDeferredIncomeExcludingPurchasedCreditImpairedLoans / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = bmrc_CommercialRealEstateInvestorFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_SubstandardMember |
Construction |  |  |  |
Financing Receivable, Recorded Investment [Line Items] |  |  |  |
Loans excluding purchased credit-impaired loans | 57,040 bmrc_LoansAndLeasesReceivableNetOfDeferredIncomeExcludingPurchasedCreditImpairedLoans / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ConstructionLoansMember |  | 48,402 bmrc_LoansAndLeasesReceivableNetOfDeferredIncomeExcludingPurchasedCreditImpairedLoans / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ConstructionLoansMember |
Total loans | 57,050 us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ConstructionLoansMember | [1] | 48,413 us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ConstructionLoansMember | [1]
Construction | Receivables Acquired with Deteriorated Credit Quality |  |  |  |
Financing Receivable, Recorded Investment [Line Items] |  |  |  |
Purchase credit-impaired | 10 us-gaap_NotesReceivableNet / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ConstructionLoansMember / us-gaap_ReceivablesAcquiredWithDeterioratedCreditQualityAxis = us-gaap_ReceivablesAcquiredWithDeterioratedCreditQualityMember |  | 11 us-gaap_NotesReceivableNet / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ConstructionLoansMember / us-gaap_ReceivablesAcquiredWithDeterioratedCreditQualityAxis = us-gaap_ReceivablesAcquiredWithDeterioratedCreditQualityMember |
Construction | Pass |  |  |  |
Financing Receivable, Recorded Investment [Line Items] |  |  |  |
Loans excluding purchased credit-impaired loans | 50,305 bmrc_LoansAndLeasesReceivableNetOfDeferredIncomeExcludingPurchasedCreditImpairedLoans / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ConstructionLoansMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_PassMember |  | 41,710 bmrc_LoansAndLeasesReceivableNetOfDeferredIncomeExcludingPurchasedCreditImpairedLoans / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ConstructionLoansMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_PassMember |
Construction | Special Mention |  |  |  |
Financing Receivable, Recorded Investment [Line Items] |  |  |  |
Loans excluding purchased credit-impaired loans | 1,078 bmrc_LoansAndLeasesReceivableNetOfDeferredIncomeExcludingPurchasedCreditImpairedLoans / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ConstructionLoansMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_SpecialMentionMember |  | 1,008 bmrc_LoansAndLeasesReceivableNetOfDeferredIncomeExcludingPurchasedCreditImpairedLoans / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ConstructionLoansMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_SpecialMentionMember |
Construction | Substandard |  |  |  |
Financing Receivable, Recorded Investment [Line Items] |  |  |  |
Loans excluding purchased credit-impaired loans | 5,657 bmrc_LoansAndLeasesReceivableNetOfDeferredIncomeExcludingPurchasedCreditImpairedLoans / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ConstructionLoansMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_SubstandardMember |  | 5,684 bmrc_LoansAndLeasesReceivableNetOfDeferredIncomeExcludingPurchasedCreditImpairedLoans / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ConstructionLoansMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_SubstandardMember |
Home equity |  |  |  |
Financing Receivable, Recorded Investment [Line Items] |  |  |  |
Loans excluding purchased credit-impaired loans | 113,210 bmrc_LoansAndLeasesReceivableNetOfDeferredIncomeExcludingPurchasedCreditImpairedLoans / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_HomeEquityMember |  | 110,721 bmrc_LoansAndLeasesReceivableNetOfDeferredIncomeExcludingPurchasedCreditImpairedLoans / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_HomeEquityMember |
Total loans | 113,277 us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_HomeEquityMember | [1] | 110,788 us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_HomeEquityMember | [1]
Home equity | Receivables Acquired with Deteriorated Credit Quality |  |  |  |
Financing Receivable, Recorded Investment [Line Items] |  |  |  |
Purchase credit-impaired | 67 us-gaap_NotesReceivableNet / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_HomeEquityMember / us-gaap_ReceivablesAcquiredWithDeterioratedCreditQualityAxis = us-gaap_ReceivablesAcquiredWithDeterioratedCreditQualityMember |  | 67 us-gaap_NotesReceivableNet / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_HomeEquityMember / us-gaap_ReceivablesAcquiredWithDeterioratedCreditQualityAxis = us-gaap_ReceivablesAcquiredWithDeterioratedCreditQualityMember |
Home equity | Pass |  |  |  |
Financing Receivable, Recorded Investment [Line Items] |  |  |  |
Loans excluding purchased credit-impaired loans | 111,227 bmrc_LoansAndLeasesReceivableNetOfDeferredIncomeExcludingPurchasedCreditImpairedLoans / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_HomeEquityMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_PassMember |  | 107,933 bmrc_LoansAndLeasesReceivableNetOfDeferredIncomeExcludingPurchasedCreditImpairedLoans / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_HomeEquityMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_PassMember |
Home equity | Special Mention |  |  |  |
Financing Receivable, Recorded Investment [Line Items] |  |  |  |
Loans excluding purchased credit-impaired loans | 321 bmrc_LoansAndLeasesReceivableNetOfDeferredIncomeExcludingPurchasedCreditImpairedLoans / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_HomeEquityMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_SpecialMentionMember |  | 322 bmrc_LoansAndLeasesReceivableNetOfDeferredIncomeExcludingPurchasedCreditImpairedLoans / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_HomeEquityMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_SpecialMentionMember |
Home equity | Substandard |  |  |  |
Financing Receivable, Recorded Investment [Line Items] |  |  |  |
Loans excluding purchased credit-impaired loans | 1,662 bmrc_LoansAndLeasesReceivableNetOfDeferredIncomeExcludingPurchasedCreditImpairedLoans / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_HomeEquityMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_SubstandardMember |  | 2,466 bmrc_LoansAndLeasesReceivableNetOfDeferredIncomeExcludingPurchasedCreditImpairedLoans / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_HomeEquityMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_SubstandardMember |
Other residential |  |  |  |
Financing Receivable, Recorded Investment [Line Items] |  |  |  |
Total loans | 73,375 us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = bmrc_OtherResidentialFinancingReceivableMember | [1],[2] | 73,035 us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = bmrc_OtherResidentialFinancingReceivableMember | [1],[2]
Other residential | Receivables Acquired with Deteriorated Credit Quality |  |  |  |
Financing Receivable, Recorded Investment [Line Items] |  |  |  |
Purchase credit-impaired | 0 us-gaap_NotesReceivableNet / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = bmrc_OtherResidentialFinancingReceivableMember / us-gaap_ReceivablesAcquiredWithDeterioratedCreditQualityAxis = us-gaap_ReceivablesAcquiredWithDeterioratedCreditQualityMember |  | 0 us-gaap_NotesReceivableNet / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = bmrc_OtherResidentialFinancingReceivableMember / us-gaap_ReceivablesAcquiredWithDeterioratedCreditQualityAxis = us-gaap_ReceivablesAcquiredWithDeterioratedCreditQualityMember |
Other residential | Pass |  |  |  |
Financing Receivable, Recorded Investment [Line Items] |  |  |  |
Total loans | 71,768 us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = bmrc_OtherResidentialFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_PassMember |  | 70,987 us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = bmrc_OtherResidentialFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_PassMember |
Other residential | Special Mention |  |  |  |
Financing Receivable, Recorded Investment [Line Items] |  |  |  |
Total loans | 0 us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = bmrc_OtherResidentialFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_SpecialMentionMember |  | 0 us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = bmrc_OtherResidentialFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_SpecialMentionMember |
Other residential | Substandard |  |  |  |
Financing Receivable, Recorded Investment [Line Items] |  |  |  |
Total loans | 1,607 us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = bmrc_OtherResidentialFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_SubstandardMember |  | 2,048 us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = bmrc_OtherResidentialFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_SubstandardMember |
Installment and other consumer |  |  |  |
Financing Receivable, Recorded Investment [Line Items] |  |  |  |
Total loans | 17,155 us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ConsumerPortfolioSegmentMember | [1] | 16,788 us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ConsumerPortfolioSegmentMember | [1]
Installment and other consumer | Receivables Acquired with Deteriorated Credit Quality |  |  |  |
Financing Receivable, Recorded Investment [Line Items] |  |  |  |
Purchase credit-impaired | 0 us-gaap_NotesReceivableNet / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ConsumerPortfolioSegmentMember / us-gaap_ReceivablesAcquiredWithDeterioratedCreditQualityAxis = us-gaap_ReceivablesAcquiredWithDeterioratedCreditQualityMember |  | 0 us-gaap_NotesReceivableNet / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ConsumerPortfolioSegmentMember / us-gaap_ReceivablesAcquiredWithDeterioratedCreditQualityAxis = us-gaap_ReceivablesAcquiredWithDeterioratedCreditQualityMember |
Installment and other consumer | Pass |  |  |  |
Financing Receivable, Recorded Investment [Line Items] |  |  |  |
Total loans | 16,816 us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ConsumerPortfolioSegmentMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_PassMember |  | 16,101 us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ConsumerPortfolioSegmentMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_PassMember |
Installment and other consumer | Special Mention |  |  |  |
Financing Receivable, Recorded Investment [Line Items] |  |  |  |
Total loans | 0 us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ConsumerPortfolioSegmentMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_SpecialMentionMember |  | 190 us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ConsumerPortfolioSegmentMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_SpecialMentionMember |
Installment and other consumer | Substandard |  |  |  |
Financing Receivable, Recorded Investment [Line Items] |  |  |  |
Total loans | $ 339 us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ConsumerPortfolioSegmentMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_SubstandardMember |  | $ 497 us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ConsumerPortfolioSegmentMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_SubstandardMember |
[1] | Amounts include net deferred loan costs of $651 thousand and $487 thousand at March 31, 2015 and December 31, 2014, respectively. Amounts are also net of unaccreted purchase discounts on non-PCI loans of $4.2 million and $4.4 million at March 31, 2015 and December 31, 2014, respectively.
[2] | Our residential loan portfolio does not include sub-prime loans, nor is it our practice to underwrite loans commonly referred to as "Alt-A mortgages", the characteristics of which are loans lacking full documentation, borrowers having low FICO scores or higher loan-to-value ratios.

X
- Definition Loans and Leases Receivable, Net of Deferred Income, Excluding Purchased Credit-impaired Loans + References No definition available. + Details
Name: | bmrc_LoansAndLeasesReceivableNetOfDeferredIncomeExcludingPurchasedCreditImpairedLoans
Namespace Prefix: | bmrc_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Details
Name: | us-gaap_FinancingReceivableRecordedInvestmentLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount before allowance and after deduction of deferred interest and fees, unamortized costs and premiums and discounts from face amounts, of loans and leases held in portfolio, including but not limited to, commercial and consumer loans. Excludes loans and leases covered under loss sharing agreements. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 4 -URI http://asc.fasb.org/extlink&oid=49124121&loc=d3e5074-111524 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 45 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=28367877&loc=d3e4428-111522 + Details
Name: | us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Net amount of the investment in a contractual right to receive money on demand or on fixed or determinable dates that is recognized as an asset in the creditor's statement of financial position. Examples include, but are not limited to, credit card receivables, notes receivable and receivables relating to lessor's rights to payments from leases other than operating leases that have been recorded as assets. Excludes trade accounts receivable with contractual maturity of one year or less and arose from the sale of goods or services. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.3) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 + Details
Name: | us-gaap_NotesReceivableNet
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

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

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

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

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

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

X
- Details
Name: | us-gaap_InternalCreditAssessmentAxis=us-gaap_PassMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_InternalCreditAssessmentAxis=us-gaap_SpecialMentionMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_InternalCreditAssessmentAxis=us-gaap_SubstandardMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_ReceivablesAcquiredWithDeterioratedCreditQualityAxis=us-gaap_ReceivablesAcquiredWithDeterioratedCreditQualityMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |