XML 74 R62.htm IDEA: XBRL DOCUMENT
v3.22.0.1

Loans and ALLL (Summary of information pertaining to TDRs) (Details) $ in Thousands | 12 Months Ended
--- | ---
Dec. 31, 2021 USD ($) loan | Dec. 31, 2020 USD ($) loan
Financing Receivable, Modifications [Line Items] |  |
Number of Loans | loan | 11 | 18
Pre-Modification Recorded Investment | $ 8,473 | $ 8,554
Post-Modification Recorded Investment | $ 8,473 | $ 8,554
Commercial other [Member] |  |
Financing Receivable, Modifications [Line Items] |  |
Number of Loans | loan | 5 | 10
Pre-Modification Recorded Investment | $ 4,761 | $ 5,224
Post-Modification Recorded Investment | $ 4,761 | $ 5,224
Agricultural other [Member] |  |
Financing Receivable, Modifications [Line Items] |  |
Number of Loans | loan | 6 | 5
Pre-Modification Recorded Investment | $ 3,712 | $ 3,194
Post-Modification Recorded Investment | $ 3,712 | $ 3,194
Residential real estate senior liens [Member] |  |
Financing Receivable, Modifications [Line Items] |  |
Number of Loans | loan | 0 | 3
Pre-Modification Recorded Investment | $ 0 | $ 136
Post-Modification Recorded Investment | $ 0 | $ 136
Below Market Interest Rate and Extension of Amortization Period [Member] |  |
Financing Receivable, Modifications [Line Items] |  |
Number of Loans | loan | 4 | 16
Pre-Modification Recorded Investment | $ 1,572 | $ 7,567
Below Market Interest Rate and Extension of Amortization Period [Member] | Commercial other [Member] |  |
Financing Receivable, Modifications [Line Items] |  |
Number of Loans | loan | 4 | 8
Pre-Modification Recorded Investment | $ 1,572 | $ 4,237
Below Market Interest Rate and Extension of Amortization Period [Member] | Agricultural other [Member] |  |
Financing Receivable, Modifications [Line Items] |  |
Number of Loans | loan | 0 | 5
Pre-Modification Recorded Investment | $ 0 | $ 3,194
Below Market Interest Rate and Extension of Amortization Period [Member] | Residential real estate senior liens [Member] |  |
Financing Receivable, Modifications [Line Items] |  |
Number of Loans | loan | 0 | 3
Pre-Modification Recorded Investment | $ 0 | $ 136
Interest Rate Below Market Reduction [Member] |  |
Financing Receivable, Modifications [Line Items] |  |
Number of Loans | loan | 7 | 2
Pre-Modification Recorded Investment | $ 6,901 | $ 987
Interest Rate Below Market Reduction [Member] | Commercial other [Member] |  |
Financing Receivable, Modifications [Line Items] |  |
Number of Loans | loan | 1 | 2
Pre-Modification Recorded Investment | $ 3,189 | $ 987
Interest Rate Below Market Reduction [Member] | Agricultural other [Member] |  |
Financing Receivable, Modifications [Line Items] |  |
Number of Loans | loan | 6 | 0
Pre-Modification Recorded Investment | $ 3,712 | $ 0
Interest Rate Below Market Reduction [Member] | Residential real estate senior liens [Member] |  |
Financing Receivable, Modifications [Line Items] |  |
Number of Loans | loan | 0 | 0
Pre-Modification Recorded Investment | $ 0 | $ 0
Principal Forgiveness |  |
Financing Receivable, Modifications [Line Items] |  |
Number of Loans | loan | 0 | 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 http://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 http://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 http://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
- 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: |

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

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

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