XML 62 R52.htm IDEA: XBRL DOCUMENT
v3.24.1.u1

Borrowed Funds (Pledged financial instruments) (Details) - USD ($) $ in Thousands | Mar. 31, 2024 | Dec. 31, 2023
--- | --- | ---
Debt Disclosure [Abstract] |  |
Total | $ 538,439 | $ 543,392
Short-term Debt [Line Items] |  |
AFS securities pledged without single maturity dates | 67,088 | 67,764
Federal Home Loan Bank, Advances, General Debt Obligations, Disclosures, Collateral Pledged | 377,896 | 391,529
Securities Sold under Agreements to Repurchase, Fair Value of Collateral | 67,088 | 67,764
Deposit Liabilities, Collateral Issued, Financial Instruments | 93,455 | 84,099
US Treasury Securities |  |
Short-term Debt [Line Items] |  |
AFS securities pledged without single maturity dates | 55,504 | 55,623
Mortgage Backed Securities, Other [Member] |  |
Short-term Debt [Line Items] |  |
AFS securities pledged without single maturity dates | 9,004 | 9,462
Collateralized Mortgage Obligations [Member] |  |
Short-term Debt [Line Items] |  |
AFS securities pledged without single maturity dates | $ 2,580 | $ 2,679

X
- Definition Pledged Financial Instruments, Available for Sale Securities, without Single Maturity Date + References No definition available. + Details
Name: | isba_PledgedFinancialInstrumentsAvailableforSaleSecuritieswithoutSingleMaturityDate
Namespace Prefix: | isba_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Pledged Financial Instruments, Not Separately Reported, Securities And Loans Receivable Pledged As Collateral + References No definition available. + Details
Name: | isba_PledgedFinancialInstrumentsNotSeparatelyReportedSecuritiesAndLoansReceivablePledgedAsCollateral
Namespace Prefix: | isba_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- References No definition available. + Details
Name: | us-gaap_DebtDisclosureAbstract
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount of securities, mortgage loans, or other financial instruments pledged as collateral for deposits. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Name Accounting Standards Codification -Topic 942 -SubTopic 405 -Section 50 -Paragraph 1 -Subparagraph (b) -Publisher FASB -URI https://asc.fasb.org//1943274/2147481047/942-405-50-1 + Details
Name: | us-gaap_DepositLiabilitiesCollateralIssuedFinancialInstruments
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount of the collateral pledged in support of federal home loan bank advances outstanding. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Topic 942 -SubTopic 470 -Name Accounting Standards Codification -Section 45 -Paragraph 1 -Publisher FASB -URI https://asc.fasb.org//1943274/2147480876/942-470-45-1 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Name Accounting Standards Codification -Topic 942 -SubTopic 470 -Section 50 -Paragraph 3 -Subparagraph (d) -Publisher FASB -URI https://asc.fasb.org//1943274/2147480848/942-470-50-3 + Details
Name: | us-gaap_FederalHomeLoanBankAdvancesGeneralDebtObligationsDisclosuresCollateralPledged1
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Fair value of securities pledged as collateral against securities sold under agreement to repurchase. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 210 -SubTopic 20 -Name Accounting Standards Codification -Section 55 -Paragraph 12 -Publisher FASB -URI https://asc.fasb.org//1943274/2147483444/210-20-55-12 + Details
Name: | us-gaap_SecuritiesSoldUnderAgreementsToRepurchaseFairValueOfCollateral
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
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 No definition available. + Details
Name: | us-gaap_ShortTermDebtLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | us-gaap_ShortTermDebtTypeAxis=us-gaap_USTreasurySecuritiesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_ShortTermDebtTypeAxis=us-gaap_MortgageBackedSecuritiesOtherMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_ShortTermDebtTypeAxis=us-gaap_CollateralizedMortgageObligationsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |