XML 56 R46.htm IDEA: XBRL DOCUMENT
v3.10.0.1

Loans and ALLL (Summary of information pertaining to TDRs) (Details) $ in Thousands | 3 Months Ended | 6 Months Ended
--- | --- | ---
Jun. 30, 2018 USD ($) loan | Jun. 30, 2017 USD ($) loan | Jun. 30, 2018 USD ($) loan | Jun. 30, 2017 USD ($) loan
Financing Receivable, Modifications [Line Items] |  |  |  |
Impaired Financing Receivable, with Related Allowance, Average Recorded Investment | $ 14,885 | $ 14,284 | $ 14,877 | $ 14,567
Impaired Financing Receivable, with Related Allowance, Interest Income, Accrual Method | $ 46 | $ 191 | $ 239 | $ 371
Number of Loans | loan | 19 | 11 | 26 | 14
Pre-Modification Recorded Investment | $ 3,762 | $ 5,786 | $ 6,244 | $ 6,021
Financing Receivable, Modifications, Post-Modification Recorded Investment | $ 3,738 | $ 5,786 | $ 6,221 | $ 6,021
Interest Rate Below Market Reduction [Member] |  |  |  |
Financing Receivable, Modifications [Line Items] |  |  |  |
Number of Loans | loan | 7 | 4 | 9 | 5
Pre-Modification Recorded Investment | $ 1,826 | $ 1,349 | $ 2,098 | $ 1,357
Below Market Interest Rate and Extension of Amortization Period [Member] |  |  |  |
Financing Receivable, Modifications [Line Items] |  |  |  |
Number of Loans | loan | 12 | 7 | 17 | 9
Pre-Modification Recorded Investment | $ 1,936 | $ 4,437 | $ 4,146 | $ 4,664
Commercial other [Member] |  |  |  |
Financing Receivable, Modifications [Line Items] |  |  |  |
Impaired Financing Receivable, with Related Allowance, Average Recorded Investment | 1,463 | 1,146 | 1,505 | 1,211
Impaired Financing Receivable, with Related Allowance, Interest Income, Accrual Method | $ 15 | $ 23 | $ 39 | $ 47
Number of Loans | loan | 1 | 1 | 4 | 3
Pre-Modification Recorded Investment | $ 105 | $ 86 | $ 1,360 | $ 313
Financing Receivable, Modifications, Post-Modification Recorded Investment | $ 105 | $ 86 | $ 1,360 | $ 313
Commercial other [Member] | Interest Rate Below Market Reduction [Member] |  |  |  |
Financing Receivable, Modifications [Line Items] |  |  |  |
Number of Loans | loan | 0 | 0 | 1 | 0
Pre-Modification Recorded Investment | $ 0 | $ 0 | $ 174 | $ 0
Commercial other [Member] | Below Market Interest Rate and Extension of Amortization Period [Member] |  |  |  |
Financing Receivable, Modifications [Line Items] |  |  |  |
Number of Loans | loan | 1 | 1 | 3 | 3
Pre-Modification Recorded Investment | $ 105 | $ 86 | $ 1,186 | $ 313
Agricultural other [Member] |  |  |  |
Financing Receivable, Modifications [Line Items] |  |  |  |
Impaired Financing Receivable, with Related Allowance, Average Recorded Investment |  |  | 0 | 34
Impaired Financing Receivable, with Related Allowance, Interest Income, Accrual Method |  |  | $ 0 | $ 0
Number of Loans | loan | 13 | 7 | 15 | 7
Pre-Modification Recorded Investment | $ 3,330 | $ 5,445 | $ 4,391 | $ 5,445
Financing Receivable, Modifications, Post-Modification Recorded Investment | $ 3,306 | $ 5,445 | $ 4,368 | $ 5,445
Agricultural other [Member] | Interest Rate Below Market Reduction [Member] |  |  |  |
Financing Receivable, Modifications [Line Items] |  |  |  |
Number of Loans | loan | 6 | 4 | 7 | 4
Pre-Modification Recorded Investment | $ 1,770 | $ 1,349 | $ 1,868 | $ 1,349
Agricultural other [Member] | Below Market Interest Rate and Extension of Amortization Period [Member] |  |  |  |
Financing Receivable, Modifications [Line Items] |  |  |  |
Number of Loans | loan | 7 | 3 | 8 | 3
Pre-Modification Recorded Investment | $ 1,560 | $ 4,096 | $ 2,523 | $ 4,096
Residential real estate senior liens [Member] |  |  |  |
Financing Receivable, Modifications [Line Items] |  |  |  |
Impaired Financing Receivable, with Related Allowance, Average Recorded Investment | 7,747 | 8,385 | 7,785 | 8,403
Impaired Financing Receivable, with Related Allowance, Interest Income, Accrual Method | $ 16 | $ 83 | $ 90 | $ 166
Number of Loans | loan | 5 | 3 | 7 | 3
Pre-Modification Recorded Investment | $ 327 | $ 255 | $ 493 | $ 255
Financing Receivable, Modifications, Post-Modification Recorded Investment | $ 327 | $ 255 | $ 493 | $ 255
Residential real estate senior liens [Member] | Interest Rate Below Market Reduction [Member] |  |  |  |
Financing Receivable, Modifications [Line Items] |  |  |  |
Number of Loans | loan | 1 | 0 | 1 | 0
Pre-Modification Recorded Investment | $ 56 | $ 0 | $ 56 | $ 0
Residential real estate senior liens [Member] | Below Market Interest Rate and Extension of Amortization Period [Member] |  |  |  |
Financing Receivable, Modifications [Line Items] |  |  |  |
Number of Loans | loan | 4 | 3 | 6 | 3
Pre-Modification Recorded Investment | $ 271 | $ 255 | $ 437 | $ 255
Residential real estate junior liens [Member] |  |  |  |
Financing Receivable, Modifications [Line Items] |  |  |  |
Impaired Financing Receivable, with Related Allowance, Average Recorded Investment | 30 | 77 | 35 | 76
Impaired Financing Receivable, with Related Allowance, Interest Income, Accrual Method | $ 0 | $ 1 | $ 0 | $ 1
Number of Loans | loan | 0 | 0 | 0 | 1
Pre-Modification Recorded Investment | $ 0 | $ 0 | $ 0 | $ 8
Financing Receivable, Modifications, Post-Modification Recorded Investment | $ 0 | $ 0 | $ 0 | $ 8
Residential real estate junior liens [Member] | Interest Rate Below Market Reduction [Member] |  |  |  |
Financing Receivable, Modifications [Line Items] |  |  |  |
Number of Loans | loan | 0 | 0 | 0 | 1
Pre-Modification Recorded Investment | $ 0 | $ 0 | $ 0 | $ 8
Residential real estate junior liens [Member] | Below Market Interest Rate and Extension of Amortization Period [Member] |  |  |  |
Financing Receivable, Modifications [Line Items] |  |  |  |
Number of Loans | loan | 0 | 0 | 0 | 0
Pre-Modification Recorded Investment | $ 0 | $ 0 | $ 0 | $ 0
Residential, Home Equity Line Of Credit, Financing Receivable [Member] |  |  |  |
Financing Receivable, Modifications [Line Items] |  |  |  |
Impaired Financing Receivable, with Related Allowance, Average Recorded Investment | 0 | 35 | 0 | 18
Impaired Financing Receivable, with Related Allowance, Interest Income, Accrual Method |  | $ 0 | $ 0 | $ 0
Total residential real estate [Member] |  |  |  |
Financing Receivable, Modifications [Line Items] |  |  |  |
Number of Loans | loan | 5 | 3 | 7 | 4
Pre-Modification Recorded Investment | $ 327 | $ 255 | $ 493 | $ 263
Financing Receivable, Modifications, Post-Modification Recorded Investment | $ 327 | $ 255 | $ 493 | $ 263
Total residential real estate [Member] | Interest Rate Below Market Reduction [Member] |  |  |  |
Financing Receivable, Modifications [Line Items] |  |  |  |
Number of Loans | loan | 1 | 0 | 1 | 1
Pre-Modification Recorded Investment | $ 56 | $ 0 | $ 56 | $ 8
Total residential real estate [Member] | Below Market Interest Rate and Extension of Amortization Period [Member] |  |  |  |
Financing Receivable, Modifications [Line Items] |  |  |  |
Number of Loans | loan | 4 | 3 | 6 | 3
Pre-Modification Recorded Investment | $ 271 | $ 255 | $ 437 | $ 255
Consumer Unsecured Financing Receivable [Member] |  |  |  |
Financing Receivable, Modifications [Line Items] |  |  |  |
Number of Loans | loan | 0 | 0 | 0 | 0
Pre-Modification Recorded Investment | $ 0 | $ 0 | $ 0 | $ 0
Financing Receivable, Modifications, Post-Modification Recorded Investment | $ 0 | $ 0 | $ 0 | $ 0
Consumer Unsecured Financing Receivable [Member] | Interest Rate Below Market Reduction [Member] |  |  |  |
Financing Receivable, Modifications [Line Items] |  |  |  |
Number of Loans | loan | 0 | 0 | 0 | 0
Pre-Modification Recorded Investment | $ 0 | $ 0 | $ 0 | $ 0
Consumer Unsecured Financing Receivable [Member] | Below Market Interest Rate and Extension of Amortization Period [Member] |  |  |  |
Financing Receivable, Modifications [Line Items] |  |  |  |
Number of Loans | loan | 0 | 0 | 0 | 0
Pre-Modification Recorded Investment | $ 0 | $ 0 | $ 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://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 33 -URI http://asc.fasb.org/extlink&oid=84173941&loc=SL6953676-111524 + Details
Name: | us-gaap_FinancingReceivableModificationsNumberOfContracts2
Namespace Prefix: | us-gaap_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | duration

X
- Definition Post-modification amount of investment in financing receivables modified by troubled debt restructurings. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 33 -URI http://asc.fasb.org/extlink&oid=84173941&loc=SL6953676-111524 + Details
Name: | us-gaap_FinancingReceivableModificationsPostModificationRecordedInvestment2
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Pre-modification amount of investment in financing receivables modified by troubled debt restructurings. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 33 -URI http://asc.fasb.org/extlink&oid=84173941&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 http://asc.fasb.org/extlink&oid=84173941&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 http://asc.fasb.org/extlink&oid=84173941&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 http://asc.fasb.org/extlink&oid=84173941&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: |

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

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