XML 44 R32.htm IDEA: XBRL DOCUMENT v3.25.1

Loans and ACL (Summary of Loan Modifications by Type) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2025	Mar. 31, 2024
Payment Deferral
Financing Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Modified in Period, Amount		$ 823
Extended Maturity
Financing Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Modified in Period, Amount	$ 2,056	15
Commercial and Industrial, Secured, Portfolio Segment | Payment Deferral
Financing Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Modified in Period, Amount		$ 0
Financing Receivable, Modified in Period, to Total Financing Receivables, Percentage		0.00%
Commercial and Industrial, Secured, Portfolio Segment | Extended Maturity
Financing Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Modified in Period, Amount	$ 532	$ 13
Financing Receivable, Modified in Period, to Total Financing Receivables, Percentage	0.24%	0.01%
Commercial Real Estate, Owner Occupied, Portfolio Segment | Payment Deferral
Financing Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Modified in Period, Amount		$ 823
Financing Receivable, Modified in Period, to Total Financing Receivables, Percentage		0.46%
Commercial Real Estate, Owner Occupied, Portfolio Segment | Extended Maturity
Financing Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Modified in Period, Amount	$ 1,524	$ 0
Financing Receivable, Modified in Period, to Total Financing Receivables, Percentage	0.83%	0.00%
Consumer, Secured, Indirect, Portfolio Segment | Payment Deferral
Financing Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Modified in Period, Amount		$ 0
Financing Receivable, Modified in Period, to Total Financing Receivables, Percentage		0.00%
Consumer, Secured, Indirect, Portfolio Segment | Extended Maturity
Financing Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Modified in Period, Amount		$ 2
Financing Receivable, Modified in Period, to Total Financing Receivables, Percentage		0.00%

X

- Definition

Percentage of financing receivable modified during period for debtor experiencing financial difficulty to total financing receivables.

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Topic 310
-SubTopic 10
-Name Accounting Standards Codification
-Section 55
-Paragraph 12A
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481933/310-10-55-12A

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 310
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 42
-Subparagraph (a)(1)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481962/310-10-50-42

+ Details

Name:	us-gaap_FinancingReceivableModificationToTotalFinancingReceivablesPercent
Namespace Prefix:	us-gaap_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

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/exampleRef
-Topic 310
-SubTopic 10
-Name Accounting Standards Codification
-Section 55
-Paragraph 12A
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481933/310-10-55-12A

Reference 2: http://fasb.org/us-gaap/role/ref/otherTransitionRef
-Topic 310
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 34
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481962/310-10-50-34

Reference 3: http://fasb.org/us-gaap/role/ref/otherTransitionRef
-Topic 310
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 33
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481962/310-10-50-33

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Topic 310
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 42
-Subparagraph (a)(2)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481962/310-10-50-42

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Topic 310
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 42
-Subparagraph (a)(1)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481962/310-10-50-42

+ Details

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

X

- Definition

Amortized cost of financing receivable modified during period for debtor experiencing financial difficulty.

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Topic 310
-SubTopic 10
-Name Accounting Standards Codification
-Section 55
-Paragraph 12A
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481933/310-10-55-12A

Reference 2: http://fasb.org/us-gaap/role/ref/otherTransitionRef
-Topic 310
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 33
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481962/310-10-50-33

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 310
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 42
-Subparagraph (a)(1)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481962/310-10-50-42

+ Details

Name:	us-gaap_FinancingReceivableModificationsPostModificationRecordedInvestment2
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

X

- Details

Name:	us-gaap_LoanRestructuringModificationAxis=us-gaap_PaymentDeferralMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_LoanRestructuringModificationAxis=us-gaap_ExtendedMaturityMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

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

X

- Details

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

X

- Details

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