XML 81 R92.htm IDEA: XBRL DOCUMENT v3.20.1

Financial Instruments with Off-Balance Sheet Risk (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Commercial lines of credit
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loan commitments and standby letters of credit, off-balance sheet	$ 287,533	$ 238,361
Revolving home equity lines
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loan commitments and standby letters of credit, off-balance sheet	189,035	189,971
Undisbursed construction loans
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loan commitments and standby letters of credit, off-balance sheet	41,033	46,229
Personal and other lines of credit
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loan commitments and standby letters of credit, off-balance sheet	9,567	14,109
Standby letters of credit
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loan commitments and standby letters of credit, off-balance sheet	1,964	2,636
Total commitments and standby letters of credit
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loan commitments and standby letters of credit, off-balance sheet	$ 529,132	491,306
Percentage of commitments expiring in 2018	33.00%
Percentage of commitments expiring between 2019 and 2025	55.00%
Percentage of commitments expiring 2026 and thereafter	12.00%
Total commitments and standby letters of credit | Interest Payable and Other Liabilities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Allowance for off-balance sheet commitments	$ 1,100	$ 958

X

- Definition

Allowance For Off Balance Sheet Commitments

+ References

No definition available.

+ Details

Name:	bmrc_AllowanceForOffBalanceSheetCommitments
Namespace Prefix:	bmrc_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

X

- Definition

Loan Commitments And Standby Letters Of Credit, Percentage Expiring, After Year Eight

+ References

No definition available.

+ Details

Name:	bmrc_LoanCommitmentsAndStandbyLettersOfCreditPercentageExpiringAfterYearEight
Namespace Prefix:	bmrc_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

X

- Definition

Loan Commitments and Standby Letters of Credit, Percentage Expiring in Next Twelve Months

+ References

No definition available.

+ Details

Name:	bmrc_LoanCommitmentsAndStandbyLettersOfCreditPercentageExpiringInNextTwelveMonths
Namespace Prefix:	bmrc_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

X

- Definition

Loan Commitments And Standby Letters of Credit, Percentage Expiring In Year Two Through Eight

+ References

No definition available.

+ Details

Name:	bmrc_LoanCommitmentsAndStandbyLettersofCreditPercentageExpiringInYearTwoThroughEight
Namespace Prefix:	bmrc_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

X

- Definition

Off-balance Sheet Arrangements, Liabilities, Current Exposure

+ References

No definition available.

+ Details

Name:	bmrc_OffBalanceSheetArrangementsLiabilitiesCurrentExposure
Namespace Prefix:	bmrc_
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

No definition available.

+ Details

Name:	us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

X

- Details

Name:	us-gaap_FinancialInstrumentAxis=bmrc_CommercialLinesOfCreditMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_FinancialInstrumentAxis=us-gaap_HomeEquityMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_FinancialInstrumentAxis=bmrc_UndisbursedConstructionLoansMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_FinancialInstrumentAxis=bmrc_ConsumerAndOtherLinesOfCreditMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_FinancialInstrumentAxis=us-gaap_FinancialStandbyLetterOfCreditMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_FinancialInstrumentAxis=bmrc_LinesOfCreditAndLettersOfCreditUnusedCommitmentsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_BalanceSheetLocationAxis=bmrc_InterestPayableAndOtherLiabilitiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: