XML 64 R54.htm IDEA: XBRL DOCUMENT v3.24.3

Allowance for Loan Credit Losses - Modifications and Unfunded Commitments (Details) $ in Thousands	3 Months Ended	9 Months Ended
	Sep. 30, 2024 USD ($) loan	Sep. 30, 2024 USD ($) loan	Sep. 30, 2023 USD ($) loan
Financing Receivable, Allowance for Credit Loss [Line Items]
Number Of Loan Modifications | loan	1	1	0
Loan with modifications outstanding principal balance	$ 1,500	$ 1,500
Percentage of commercial loan segment with loan modifications		0.13%
Beginning Balance		$ 19,543	$ 20,208
Provision for (recovery of) credit losses		(667)	(2,471)
Ending balance	18,481	18,481	20,036
Cumulative Effect, Period of Adoption, Adjustment
Financing Receivable, Allowance for Credit Loss [Line Items]
Beginning Balance			2,165
Unfunded loan commitments
Financing Receivable, Allowance for Credit Loss [Line Items]
Beginning Balance		620	303
Provision for (recovery of) credit losses		397	(132)
Ending balance	$ 1,017	$ 1,017	908
Unfunded loan commitments | Cumulative Effect, Period of Adoption, Adjustment
Financing Receivable, Allowance for Credit Loss [Line Items]
Beginning Balance			$ 737

X

- Definition

Amount outstanding principal balance of financing receivables with loan modifications.

+ References

No definition available.

+ Details

Name:	jmsb_FinancingReceivableLoanModificationsPrincipalBalanceOutstanding
Namespace Prefix:	jmsb_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

X

- Definition

Number of loan modifications during the period.

+ References

No definition available.

+ Details

Name:	jmsb_NumberOfLoanModifications
Namespace Prefix:	jmsb_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

X

- Definition

Percentage of the commercial loan segment with loan modifications.

+ References

No definition available.

+ Details

Name:	jmsb_PercentageOfCommercialLoanSegmentWithLoanModification
Namespace Prefix:	jmsb_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

X

- Definition

Amount excluding accrued interest, of allowance for credit loss on financing receivable. Excludes net investment in lease.

+ 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

+ Details

Name:	us-gaap_FinancingReceivableAllowanceForCreditLossExcludingAccruedInterest
Namespace Prefix:	us-gaap_
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

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name Regulation S-K (SK)
-Number 229
-Section 1405
-Paragraph c
-Publisher SEC

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 13
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479319/326-20-50-13

+ Details

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

X

- Definition

Amount, excluding accrued interest, of credit loss expense (reversal of expense) on financing receivable. Excludes net investment in lease.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 13
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479319/326-20-50-13

+ Details

Name:	us-gaap_FinancingReceivableExcludingAccruedInterestCreditLossExpenseReversal
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

X

- Details

Name:	srt_CumulativeEffectPeriodOfAdoptionAxis=srt_CumulativeEffectPeriodOfAdoptionAdjustmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=us-gaap_UnfundedLoanCommitmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: