XML 47 R38.htm IDEA: XBRL DOCUMENT v3.22.2.2

Investment Securities - Pledged and Transferred Securities (Details) - USD ($) $ in Thousands	Sep. 30, 2022	Dec. 31, 2021
Financial Instruments Owned and Pledged as Collateral [Line Items]
Available-for-sale securities pledged as collateral	$ 196,533	$ 217,849
State of California
Financial Instruments Owned and Pledged as Collateral [Line Items]
Available-for-sale securities pledged as collateral	194,689	215,204
Public deposits
Financial Instruments Owned and Pledged as Collateral [Line Items]
Available-for-sale securities pledged as collateral	193,479	213,861
Trust deposits
Financial Instruments Owned and Pledged as Collateral [Line Items]
Available-for-sale securities pledged as collateral	656	729
Internal checking account
Financial Instruments Owned and Pledged as Collateral [Line Items]
Available-for-sale securities pledged as collateral	554	614
Bankruptcy trustee deposits
Financial Instruments Owned and Pledged as Collateral [Line Items]
Available-for-sale securities pledged as collateral	$ 1,844	$ 2,645

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

X

- Definition

Fair value of the securities pledged as collateral against securities loaned.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 20
-Section 55
-Paragraph 12
-URI https://asc.fasb.org/extlink&oid=99393222&loc=SL20226013-175313

+ Details

Name:	us-gaap_SecuritiesLoanedFairValueOfCollateral
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

X

- Details

Name:	us-gaap_InvestmentTypeAxis=bmrc_PledgedToStateOfCaliforniaMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_InvestmentTypeAxis=bmrc_PublicDepositsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_InvestmentTypeAxis=bmrc_TrustDepositsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_InvestmentTypeAxis=bmrc_CheckingAccountWealthManagementAndTrustServicesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_InvestmentTypeAxis=bmrc_BankruptcyTrusteeDepositsPledgedWithFederalReserveBankMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: