XML 76 R58.htm IDEA: XBRL DOCUMENT v3.25.0.1

Investment Securities - Schedule of Bond Ratings For Held-to-Maturity Securities (Details) - USD ($) $ in Thousands	Dec. 31, 2024	Dec. 31, 2023
Debt Securities, Held-to-maturity, Credit Quality Indicator [Line Items]
Held to maturity, amortized cost	$ 879,199	$ 925,198
Obligations of state and political subdivisions
Debt Securities, Held-to-maturity, Credit Quality Indicator [Line Items]
Held to maturity, amortized cost	61,560	62,034
Corporate bonds
Debt Securities, Held-to-maturity, Credit Quality Indicator [Line Items]
Held to maturity, amortized cost	30,000	30,000
Moody's And/Or Standard & Poor's AAA Rating | Obligations of state and political subdivisions
Debt Securities, Held-to-maturity, Credit Quality Indicator [Line Items]
Held to maturity, amortized cost	42,161	42,577
Moody's And/Or Standard & Poor's AAA Rating | Corporate bonds
Debt Securities, Held-to-maturity, Credit Quality Indicator [Line Items]
Held to maturity, amortized cost	0	0
Moody's And/Or Standard & Poor's AA Rating | Obligations of state and political subdivisions
Debt Securities, Held-to-maturity, Credit Quality Indicator [Line Items]
Held to maturity, amortized cost	19,399	19,457
Moody's And/Or Standard & Poor's AA Rating | Corporate bonds
Debt Securities, Held-to-maturity, Credit Quality Indicator [Line Items]
Held to maturity, amortized cost	0	0
Moody's And/Or Standard & Poor's A Rating | Obligations of state and political subdivisions
Debt Securities, Held-to-maturity, Credit Quality Indicator [Line Items]
Held to maturity, amortized cost	0	0
Moody's And/Or Standard & Poor's A Rating | Corporate bonds
Debt Securities, Held-to-maturity, Credit Quality Indicator [Line Items]
Held to maturity, amortized cost	$ 30,000	$ 30,000

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

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 5
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479319/326-20-50-5

+ Details

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

X

- Definition

Amount excluding accrued interest, before allowance for credit loss, of investment in debt security measured at amortized cost (held-to-maturity).

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 45
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479344/326-20-45-1

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 3B
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479319/326-20-50-3B

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 5
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479319/326-20-50-5

+ Details

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

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:	bmrc_CreditRatingMoodysAndOrStandardPoorsAxis=bmrc_MoodysAndOrStandardPoorsAAARatingMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	bmrc_CreditRatingMoodysAndOrStandardPoorsAxis=bmrc_MoodysAndOrStandardPoorsAARatingMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	bmrc_CreditRatingMoodysAndOrStandardPoorsAxis=bmrc_MoodysAndOrStandardPoorsARatingMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: