XML 59 R47.htm IDEA: XBRL DOCUMENT
v3.25.1

Fair Value (Quantitative information about impaired loans) (Details) - Discounted appraisal value [Member] - Level 3 [Member] - USD ($) $ in Thousands | 3 Months Ended | 12 Months Ended
--- | --- | ---
Mar. 31, 2025 | Dec. 31, 2024
Fair Value Measurement Inputs and Valuation Techniques [Line Items] |  |
Discounted appraisal value at fair value | $ 145 | $ 254
Real Estate [Member] |  |
Fair Value Measurement Inputs and Valuation Techniques [Line Items] |  |
ImpairedFinancingReceivableFairValueDisclosureAppraisedValueDiscount | 20.00% | 20.00%
ImpairedFinancingReceivableFairValueDisclosureAppraisedValueWeightedAverage | 20.00% | 20.00%

X
- Definition Impaired Financing Receivable, Fair Value Disclosure + References No definition available. + Details
Name: | isba_ImpairedFinancingReceivableFairValueDisclosure
Namespace Prefix: | isba_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Impaired Financing Receivable, Fair Value Disclosure, Appraised Value Discount + References No definition available. + Details
Name: | isba_ImpairedFinancingReceivableFairValueDisclosureAppraisedValueDiscount
Namespace Prefix: | isba_
Data Type: | dtr-types:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition ImpairedFinancingReceivableFairValueDisclosureAppraisedValueWeightedAverage + References No definition available. + Details
Name: | isba_ImpairedFinancingReceivableFairValueDisclosureAppraisedValueWeightedAverage
Namespace Prefix: | isba_
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 805 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 8 -Publisher FASB -URI https://asc.fasb.org/1943274/2147479328/805-10-50-8 Reference 2: http://www.xbrl.org/2003/role/exampleRef -Topic 805 -SubTopic 10 -Name Accounting Standards Codification -Section 55 -Paragraph 43 -Publisher FASB -URI https://asc.fasb.org/1943274/2147479303/805-10-55-43 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Topic 820 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (bbb)(1) -Publisher FASB -URI https://asc.fasb.org/1943274/2147482106/820-10-50-2 Reference 4: http://www.xbrl.org/2003/role/exampleRef -Topic 820 -SubTopic 10 -Name Accounting Standards Codification -Section 55 -Paragraph 103 -Publisher FASB -URI https://asc.fasb.org/1943274/2147482078/820-10-55-103 Reference 5: http://www.xbrl.org/2003/role/disclosureRef -Topic 820 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (bbb)(2)(i) -Publisher FASB -URI https://asc.fasb.org/1943274/2147482106/820-10-50-2 Reference 6: http://www.xbrl.org/2003/role/disclosureRef -Topic 820 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (bbb)(2) -Publisher FASB -URI https://asc.fasb.org/1943274/2147482106/820-10-50-2 + Details
Name: | us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisValuationTechniquesLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | us-gaap_ValuationTechniqueAxis=isba_DiscountedAppraisalValueValuationTechniqueMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FairValueByFairValueHierarchyLevelAxis=us-gaap_FairValueInputsLevel3Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FairValueByAssetClassAxis=isba_LoansReceivableCollateralizedByRealEstateMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |