XML 55 R46.htm IDEA: XBRL DOCUMENT
v3.22.2.2

Loans and ALLL (Summary of information pertaining to TDRs) (Details) $ in Thousands | 3 Months Ended | 9 Months Ended
--- | --- | ---
Sep. 30, 2022 USD ($) loan | Sep. 30, 2021 USD ($) loan | Sep. 30, 2022 USD ($) loan | Sep. 30, 2021 USD ($) loan
Financing Receivable, Troubled Debt Restructuring [Line Items] |  |  |  |
Impaired Financing Receivable, with Related Allowance, Average Recorded Investment | $ 4,528 | $ 8,146 | $ 5,630 | $ 8,601
Impaired Financing Receivable, with Related Allowance, Interest Income, Accrual Method | 34 | 75 | $ 168 | $ 263
Number of Loans | loan |  |  | 2 | 11
Pre-Modification Recorded Investment |  |  | $ 153 | $ 8,473
Financing Receivable, Troubled Debt Restructuring, Postmodification |  |  | $ 153 | $ 8,473
Interest Rate Below Market Reduction [Member] |  |  |  |
Financing Receivable, Troubled Debt Restructuring [Line Items] |  |  |  |
Number of Loans | loan |  |  | 1 | 7
Pre-Modification Recorded Investment |  |  | $ 55 | $ 6,901
Below Market Interest Rate and Extension of Amortization Period [Member] |  |  |  |
Financing Receivable, Troubled Debt Restructuring [Line Items] |  |  |  |
Number of Loans | loan |  |  | 1 | 4
Pre-Modification Recorded Investment |  |  | $ 98 | $ 1,572
Commercial other [Member] |  |  |  |
Financing Receivable, Troubled Debt Restructuring [Line Items] |  |  |  |
Impaired Financing Receivable, with Related Allowance, Average Recorded Investment | 1,413 | 3,090 | 2,299 | 1,569
Impaired Financing Receivable, with Related Allowance, Interest Income, Accrual Method | $ 0 | $ 35 | $ 62 | $ 71
Number of Loans | loan | 1 | 0 | 1 | 5
Pre-Modification Recorded Investment | $ 55 | $ 0 | $ 55 | $ 4,761
Financing Receivable, Troubled Debt Restructuring, Postmodification | $ 55 | $ 0 | $ 55 | $ 4,761
Commercial other [Member] | Interest Rate Below Market Reduction [Member] |  |  |  |
Financing Receivable, Troubled Debt Restructuring [Line Items] |  |  |  |
Number of Loans | loan | 1 | 0 | 1 | 1
Pre-Modification Recorded Investment | $ 55 | $ 0 | $ 55 | $ 3,189
Commercial other [Member] | Below Market Interest Rate and Extension of Amortization Period [Member] |  |  |  |
Financing Receivable, Troubled Debt Restructuring [Line Items] |  |  |  |
Number of Loans | loan | 0 | 0 | 0 | 4
Pre-Modification Recorded Investment | $ 0 | $ 0 | $ 0 | $ 1,572
Agricultural other [Member] |  |  |  |
Financing Receivable, Troubled Debt Restructuring [Line Items] |  |  |  |
Impaired Financing Receivable, with Related Allowance, Average Recorded Investment |  |  | 0 | 226
Impaired Financing Receivable, with Related Allowance, Interest Income, Accrual Method |  |  | $ 0 | $ 0
Number of Loans | loan |  |  | 0 | 6
Pre-Modification Recorded Investment |  |  | $ 0 | $ 3,712
Financing Receivable, Troubled Debt Restructuring, Postmodification |  |  | $ 0 | $ 3,712
Agricultural other [Member] | Interest Rate Below Market Reduction [Member] |  |  |  |
Financing Receivable, Troubled Debt Restructuring [Line Items] |  |  |  |
Number of Loans | loan |  |  | 0 | 6
Pre-Modification Recorded Investment |  |  | $ 0 | $ 3,712
Agricultural other [Member] | Below Market Interest Rate and Extension of Amortization Period [Member] |  |  |  |
Financing Receivable, Troubled Debt Restructuring [Line Items] |  |  |  |
Number of Loans | loan |  |  | 0 | 0
Pre-Modification Recorded Investment |  |  | $ 0 | $ 0
Residential real estate senior liens [Member] |  |  |  |
Financing Receivable, Troubled Debt Restructuring [Line Items] |  |  |  |
Impaired Financing Receivable, with Related Allowance, Average Recorded Investment | 2,927 | 3,585 | 3,141 | 3,908
Impaired Financing Receivable, with Related Allowance, Interest Income, Accrual Method | $ 31 | $ 37 | $ 97 | $ 115
Number of Loans | loan |  |  | 1 | 0
Pre-Modification Recorded Investment |  |  | $ 98 | $ 0
Financing Receivable, Troubled Debt Restructuring, Postmodification |  |  | $ 98 | $ 0
Residential real estate senior liens [Member] | Interest Rate Below Market Reduction [Member] |  |  |  |
Financing Receivable, Troubled Debt Restructuring [Line Items] |  |  |  |
Number of Loans | loan |  |  | 0 | 0
Pre-Modification Recorded Investment |  |  | $ 0 | $ 0
Residential real estate senior liens [Member] | Below Market Interest Rate and Extension of Amortization Period [Member] |  |  |  |
Financing Receivable, Troubled Debt Restructuring [Line Items] |  |  |  |
Number of Loans | loan |  |  | 1 | 0
Pre-Modification Recorded Investment |  |  | $ 98 | $ 0

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_FinancingReceivableModificationsLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Number of financing receivables that have been modified by troubled debt restructurings. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 33 -URI https://asc.fasb.org/extlink&oid=123577603&loc=SL6953676-111524 + Details
Name: | us-gaap_FinancingReceivableModificationsNumberOfContracts2
Namespace Prefix: | us-gaap_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount, after troubled debt restructuring, of modified financing receivable. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 33 -URI https://asc.fasb.org/extlink&oid=123577603&loc=SL6953676-111524 + Details
Name: | us-gaap_FinancingReceivableModificationsPostModificationRecordedInvestment2
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Amount, before troubled debt restructuring, of financing receivable to be modified. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 33 -URI https://asc.fasb.org/extlink&oid=123577603&loc=SL6953676-111524 + Details
Name: | us-gaap_FinancingReceivableModificationsPreModificationRecordedInvestment2
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Amount of average investment of impaired financing receivables for which there is a related allowance for credit losses. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 15 -Subparagraph (c)(1) -URI https://asc.fasb.org/extlink&oid=123577603&loc=d3e5212-111524 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 17 -URI https://asc.fasb.org/extlink&oid=123577603&loc=d3e5258-111524 + Details
Name: | us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceAverageRecordedInvestment
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Amount of interest income, recognized on accrual basis, on financing receivables, for which there is a related allowance for credit losses and are recognized as impaired. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 15 -Subparagraph (c)(2) -URI https://asc.fasb.org/extlink&oid=123577603&loc=d3e5212-111524 + Details
Name: | us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceInterestIncomeAccrualMethod
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Details
Name: | us-gaap_LoanRestructuringModificationAxis=us-gaap_InterestRateBelowMarketReductionMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_LoanRestructuringModificationAxis=isba_BelowMarketInterestRateAndExtensionOfAmortizationPeriodMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

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