XML 53 R44.htm IDEA: XBRL DOCUMENT
v3.23.3

Loans and ACL (Summary of Nonaccrual Loans With No ACL) (Details) - USD ($) $ in Thousands | Sep. 30, 2023 | Dec. 31, 2022
--- | --- | ---
Financing Receivable, Nonaccrual [Line Items] |  |
Loans and Leases Receivable, Nonperforming, Nonaccrual of Interest | $ 520 | $ 457
Financing Receivable, Nonaccrual, No Allowance | 520 | 437
Commercial and Industrial, Secured, Portfolio Segment |  |
Financing Receivable, Nonaccrual [Line Items] |  |
Loans and Leases Receivable, Nonperforming, Nonaccrual of Interest | 17 | 22
Financing Receivable, Nonaccrual, No Allowance | 17 | 22
Commercial Real Estate, 1-4 Family Investor, Portfolio Segment |  |
Financing Receivable, Nonaccrual [Line Items] |  |
Loans and Leases Receivable, Nonperforming, Nonaccrual of Interest | 0 | 74
Financing Receivable, Nonaccrual, No Allowance | 0 | 74
Agricultural Mortgage, Portfolio Segment |  |
Financing Receivable, Nonaccrual [Line Items] |  |
Loans and Leases Receivable, Nonperforming, Nonaccrual of Interest | 41 | 67
Financing Receivable, Nonaccrual, No Allowance | 41 | 67
Agricultural Other Portfolio Segment [Member] |  |
Financing Receivable, Nonaccrual [Line Items] |  |
Loans and Leases Receivable, Nonperforming, Nonaccrual of Interest | 167 | 167
Financing Receivable, Nonaccrual, No Allowance | 167 | 167
Residential, Senior Liens, Financing Receivable [Member] |  |
Financing Receivable, Nonaccrual [Line Items] |  |
Loans and Leases Receivable, Nonperforming, Nonaccrual of Interest | 295 | 127
Financing Receivable, Nonaccrual, No Allowance | $ 295 | $ 107

X
- Definition Amortized cost of financing receivable on nonaccrual status with no allowance for credit loss. 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 16 -Subparagraph (d) -Publisher FASB -URI https://asc.fasb.org//1943274/2147479319/326-20-50-16 + Details
Name: | us-gaap_FinancingReceivableNonaccrualNoAllowance
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 Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 326 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 16 -Publisher FASB -URI https://asc.fasb.org//1943274/2147479319/326-20-50-16 + Details
Name: | us-gaap_FinancingReceivableNonaccrualStatusLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Reflects the carrying amount of loans deemed to be questionable as to collection on which no interest is continuing to be recognized. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 7 -Subparagraph (a) -Publisher FASB -URI https://asc.fasb.org//1943274/2147481962/310-10-50-7 + Details
Name: | us-gaap_LoansAndLeasesReceivableImpairedNonperformingNonaccrualOfInterest
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_CommercialRealEstate14FamilyInvestorPortfolioSegmentMember
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_ResidentialSeniorLiensFinancingReceivableMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |