XML 76 R63.htm IDEA: XBRL DOCUMENT
v3.25.0.1

Loans and ACL (Narrative) (Details) $ in Thousands | 12 Months Ended
--- | ---
Dec. 31, 2024 USD ($) | Dec. 31, 2023 USD ($)
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |
Threshold period of continuous performance to return loans to accrual status | 6 months |
Advance in connection with impaired loans | $ 43 | $ 0
Financing Receivable, Modified, Subsequent Default | 0 | 0
Collateral Pledged |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |
Individually Evaluated for Impairment, Loans | $ 254 | 1,083
Minimum [Member] | 4 - Low satisfactory [Member] |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |
Delinquency period | 10 days |
Minimum [Member] | 5 - Special mention [Member] |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |
Financing Receivable, Threshold Period Past Due | 30 days |
Maximum [Member] |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |
Financing receivable, amortization term | 30 years |
Maximum [Member] | 4 - Low satisfactory [Member] |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |
Delinquency period | 30 days |
Maximum [Member] | 5 - Special mention [Member] |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |
Financing Receivable, Threshold Period Past Due | 60 days |
Commercial and Agricultural Portfolio Segments [Member] |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |
Maximum percentage of loan | 0.80 |
Commercial and Agricultural Portfolio Segments [Member] | Customer Concentration Risk [Member] |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |
Maximum amount of loans | $ 18 |
Residential Real Estate [Member] |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |
Maximum percentage of loan | 1 |
Maximum percentage of principal, interest, taxes and hazard insurance on property over gross income | 0.28 |
Maximum percentage of debt servicing over gross income | 0.40 |
Maximum amount without corporation approval | $ 1 |
Residential, Privately Insured, Financing Receivable [Member] |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |
Maximum percentage of loan | 0.80 |
Consumer [Member] |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |
Maximum days of consumer loan charged off | 180 days |
Consumer [Member] | Collateral Pledged |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |
Individually Evaluated for Impairment, Loans | $ 0 | $ 0
Consumer [Member] | Maximum [Member] |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |
Financing receivable, amortization term | 15 years |
Commercial, Agricultural, and Residential Portfolio [Member] |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |
Number of days past due (or more), accrual of interest discontinued | 90 days |

X
- Definition Financing Receivable, Amount, Additional Approval Threshold + References No definition available. + Details
Name: | isba_FinancingReceivableAmountAdditionalApprovalThreshold
Namespace Prefix: | isba_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Financing Receivable, Continuing Performance, Accrual Of Interest, Threshold Period + References No definition available. + Details
Name: | isba_FinancingReceivableContinuingPerformanceAccrualOfInterestThresholdPeriod
Namespace Prefix: | isba_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Definition Financing Receivable, Credit Quality, Delinquency Period + References No definition available. + Details
Name: | isba_FinancingReceivableCreditQualityDelinquencyPeriod
Namespace Prefix: | isba_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Definition Financing Receivable, Debt Servicing To Gross Income Ratio, Maximum + References No definition available. + Details
Name: | isba_FinancingReceivableDebtServicingToGrossIncomeRatioMaximum
Namespace Prefix: | isba_
Data Type: | xbrli:pureItemType
Balance Type: | na
Period Type: | duration

X
- Definition Financing Receivable, Loan To Value Ratio, Maximum + References No definition available. + Details
Name: | isba_FinancingReceivableLoanToValueRatioMaximum
Namespace Prefix: | isba_
Data Type: | xbrli:pureItemType
Balance Type: | na
Period Type: | duration

X
- Definition Financing Receivable, Nonperforming, Nonaccrual Of Interest, Threshold Period + References No definition available. + Details
Name: | isba_FinancingReceivableNonperformingNonaccrualOfInterestThresholdPeriod
Namespace Prefix: | isba_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Definition Financing Receivable, Payment Amount To Gross Income Ratio, Maximum + References No definition available. + Details
Name: | isba_FinancingReceivablePaymentAmountToGrossIncomeRatioMaximum
Namespace Prefix: | isba_
Data Type: | xbrli:pureItemType
Balance Type: | na
Period Type: | duration

X
- Definition Financing Receivable, Term + References No definition available. + Details
Name: | isba_FinancingReceivableTerm
Namespace Prefix: | isba_
Data Type: | xbrli:durationItemType
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/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 Maximum amount of loss due to credit risk that, based on the gross fair value of the financial instrument, the entity would incur if parties to the financial instruments that make up the concentration failed completely to perform according to the terms of the contracts and the collateral or other security, if any, for the amount due proved to be of no value to the entity. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Name Accounting Standards Codification -Topic 825 -SubTopic 10 -Section 50 -Paragraph 21 -Subparagraph (b) -Publisher FASB -URI https://asc.fasb.org/1943274/2147482907/825-10-50-21 + Details
Name: | us-gaap_ConcentrationRiskCreditRiskFinancialInstrumentMaximumExposure
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Amount of financing receivable individually evaluated for credit loss. Excludes financing receivable collectively evaluated for credit loss. + References Reference 1: http://www.xbrl.org/2003/role/exampleRef -Topic 310 -SubTopic 10 -Name Accounting Standards Codification -Section S99 -Paragraph 4 -Subparagraph (SAB Topic 6.L.5.a) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480418/310-10-S99-4 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Topic 310 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 11C -Subparagraph (b) -Publisher FASB -URI https://asc.fasb.org/1943274/2147481962/310-10-50-11C + Details
Name: | us-gaap_FinancingReceivableIndividuallyEvaluatedForImpairment
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amortized cost of financing receivable with payment default in current period and modified within previous 12 months preceding payment default for debtor experiencing financial difficulty. + References Reference 1: http://fasb.org/us-gaap/role/ref/otherTransitionRef -Topic 310 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 34 -Subparagraph (a)(2) -Publisher FASB -URI https://asc.fasb.org/1943274/2147481962/310-10-50-34 Reference 2: 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 3: http://www.xbrl.org/2003/role/disclosureRef -Topic 310 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 44 -Subparagraph (a)(2) -Publisher FASB -URI https://asc.fasb.org/1943274/2147481962/310-10-50-44 + Details
Name: | us-gaap_FinancingReceivableModificationsSubsequentDefaultRecordedInvestment1
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Threshold period for when financing receivable is considered past due, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. Excludes threshold period past due to write off as uncollectible. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 326 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 14 -Publisher FASB -URI https://asc.fasb.org/1943274/2147479319/326-20-50-14 + Details
Name: | us-gaap_FinancingReceivableThresholdPeriodPastDue
Namespace Prefix: | us-gaap_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | instant

X
- Definition Threshold period for when financing receivable is considered past due to write off as uncollectible, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 326 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 14 -Publisher FASB -URI https://asc.fasb.org/1943274/2147479319/326-20-50-14 + Details
Name: | us-gaap_FinancingReceivableThresholdPeriodPastDueWriteoff
Namespace Prefix: | us-gaap_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | instant

X
- Definition Amount of commitment to lend additional funds to debtor experiencing financial difficulty for which creditor has modified terms of financing receivable. + References Reference 1: http://fasb.org/us-gaap/role/ref/otherTransitionRef -Topic 310 -SubTopic 40 -Name Accounting Standards Codification -Section 50 -Paragraph 1 -Publisher FASB -URI https://asc.fasb.org/1943274/2147481746/310-40-50-1 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Topic 310 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 36 -Publisher FASB -URI https://asc.fasb.org/1943274/2147481962/310-10-50-36 + Details
Name: | us-gaap_LoansAndLeasesReceivableImpairedCommitmentToLend
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Details
Name: | us-gaap_CollateralAxis=us-gaap_CollateralPledgedMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_RangeAxis=srt_MinimumMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_InternalCreditAssessmentAxis=isba_LowSatisfactoryRatingMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_InternalCreditAssessmentAxis=us-gaap_SpecialMentionMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_RangeAxis=srt_MaximumMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=isba_CommercialAndAgriculturalPortfolioSegmentMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_ConcentrationRiskByTypeAxis=us-gaap_CustomerConcentrationRiskMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=us-gaap_ResidentialPortfolioSegmentMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=isba_ResidentialPrivatelyInsuredFinancingReceivableMember
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: |

X
- Details
Name: | us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=isba_CommercialAgriculturalandResidentialPortfolioSegmentsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |