XML 40 R28.htm IDEA: XBRL DOCUMENT v3.25.1

Loans and ACL (Summary of Loan Composition) (Details) - USD ($) $ in Thousands	Mar. 31, 2025	Dec. 31, 2024
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss	$ 1,367,724	$ 1,423,571
Financing Receivable, before Allowance for Credit Loss, to Total, Percent	100.00%	100.00%
Commercial and Industrial, Secured, Portfolio Segment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss	$ 220,884	$ 221,510
Financing Receivable, before Allowance for Credit Loss, to Total, Percent	16.15%	15.56%
Commercial and Industrial, Unsecured, Portfolio Segment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss	$ 28,336	$ 23,384
Financing Receivable, before Allowance for Credit Loss, to Total, Percent	2.07%	1.64%
Commercial [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss	$ 249,220	$ 244,894
Financing Receivable, before Allowance for Credit Loss, to Total, Percent	18.22%	17.20%
Commercial Real Estate, Owner Occupied, Portfolio Segment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss	$ 183,228	$ 178,376
Financing Receivable, before Allowance for Credit Loss, to Total, Percent	13.40%	12.53%
Commercial Real Estate, Non-owner Occupied
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss	$ 206,976	$ 208,118
Financing Receivable, before Allowance for Credit Loss, to Total, Percent	15.13%	14.62%
Commercial Real Estate, 1-4 Family Investor, Portfolio Segment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss	$ 93,845	$ 92,497
Financing Receivable, before Allowance for Credit Loss, to Total, Percent	6.86%	6.50%
Commercial Real Estate, Multifamily, Portfolio Segment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss	$ 68,185	$ 68,456
Financing Receivable, before Allowance for Credit Loss, to Total, Percent	4.99%	4.81%
Commercial Real Estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss	$ 552,234	$ 547,447
Financing Receivable, before Allowance for Credit Loss, to Total, Percent	40.38%	38.46%
Commercial Advances to Mortgage Brokers Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss	$ 3,015	$ 63,080
Financing Receivable, before Allowance for Credit Loss, to Total, Percent	0.22%	4.43%
Agricultural Mortgage, Portfolio Segment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss	$ 65,699	$ 67,550
Financing Receivable, before Allowance for Credit Loss, to Total, Percent	4.80%	4.75%
Agricultural Other Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss	$ 28,660	$ 32,144
Financing Receivable, before Allowance for Credit Loss, to Total, Percent	2.10%	2.26%
Agricultural [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss	$ 94,359	$ 99,694
Financing Receivable, before Allowance for Credit Loss, to Total, Percent	6.90%	7.01%
Residential Real Estate, Senior Lien, Portfolio Segment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss	$ 337,542	$ 332,743
Financing Receivable, before Allowance for Credit Loss, to Total, Percent	24.68%	23.37%
Residential Real Estate, Junior Lien, Portfolio Segment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss	$ 9,409	$ 8,655
Financing Receivable, before Allowance for Credit Loss, to Total, Percent	0.69%	0.61%
Residential Real Estate, Home Equity Lines of Credit, Portfolio Segment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss	$ 40,397	$ 39,474
Financing Receivable, before Allowance for Credit Loss, to Total, Percent	2.95%	2.77%
Residential Mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss	$ 387,348	$ 380,872
Financing Receivable, before Allowance for Credit Loss, to Total, Percent	28.32%	26.75%
Consumer, Secured, Direct, Portfolio Segment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss	$ 33,220	$ 35,050
Financing Receivable, before Allowance for Credit Loss, to Total, Percent	2.42%	2.46%
Consumer, Secured, Indirect, Portfolio Segment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss	$ 45,081	$ 49,136
Financing Receivable, before Allowance for Credit Loss, to Total, Percent	3.30%	3.45%
Consumer, Unsecured, Portfolio Segment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss	$ 3,247	$ 3,398
Financing Receivable, before Allowance for Credit Loss, to Total, Percent	0.24%	0.24%
Consumer Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss	$ 81,548	$ 87,584
Financing Receivable, before Allowance for Credit Loss, to Total, Percent	5.96%	6.15%

X

- Definition

Percentage, before allowance for credit loss, of financing receivable to total financing receivable.

+ References

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

+ Details

Name:	srt_FinancingReceivableBeforeAllowanceForCreditLossToTotalPercent
Namespace Prefix:	srt_
Data Type:	dtr-types:percentItemType
Balance Type:	na
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/2009/role/commonPracticeRef
-Topic 310
-SubTopic 20
-Name Accounting Standards Codification
-Section 40
-Paragraph 7
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481628/310-20-40-7

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 310
-SubTopic 10
-Name Accounting Standards Codification
-Section 45
-Paragraph 2
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481990/310-10-45-2

+ Details

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

X

- Definition

Amortized cost excluding accrued interest, before allowance for credit loss, of 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

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

X

- Details

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

X

- Details

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

X

- Details

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

X

- Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=isba_CommercialRealEstate14FamilyInvestorPortfolioSegmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

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

X

- Details

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

X

- Details

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

X

- Details

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

X

- Details

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

X

- Details

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

X

- Details

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

X

- Details

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

X

- Details

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

X

- Details

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

X

- Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=isba_ConsumerSecuredDirectPortfolioSegmentMember
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:

X

- Details

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

X

- Details

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