XML 56 R46.htm IDEA: XBRL DOCUMENT
v3.21.2

Loans and ALLL (Summary of information pertaining to impaired loans) (Details) - USD ($) $ in Thousands | 3 Months Ended | 6 Months Ended |
--- | --- | --- | ---
Jun. 30, 2021 | Jun. 30, 2020 | Jun. 30, 2021 | Jun. 30, 2020 | Dec. 31, 2020
Impaired Financing Receivable, Recorded Investment [Abstract] |  |  |  |  |
Impaired loans with a valuation allowance, Outstanding Balance | $ 9,558 |  | $ 9,558 |  | $ 9,823
Impaired loans without a valuation allowance, Outstanding Balance | 20,977 |  | 20,977 |  | 18,113
Impaired loans, Outstanding Balance | 30,535 |  | 30,535 |  | 27,936
Impaired Financing Receivable, Unpaid Principal Balance [Abstract] |  |  |  |  |
Impaired loans with a valuation allowance, Unpaid Principal Balance | 9,880 |  | 9,880 |  | 10,407
Impaired loans without a valuation allowance, Unpaid Principal Balance | 21,293 |  | 21,293 |  | 18,237
Impaired loans, Unpaid Principal Balance | 31,173 |  | 31,173 |  | 28,644
Impaired loans, Valuation Allowance | 1,201 |  | 1,201 |  | 911
Impaired Financing Receivable, Average Recorded Investment [Abstract] |  |  |  |  |
Impaired loans with a valuation allowance, Average Outstanding Balance | 8,763 | $ 10,174 | 8,828 | $ 10,014 |
Impaired loans without a valuation allowance, Average Outstanding Balance | 23,454 | 16,822 | 22,738 | 17,441 |
Impaired loans, Average Outstanding Balance | 32,217 | 26,996 | 31,566 | 27,455 |
Impaired Financing Receivable, Interest Income, Accrual Method [Abstract] |  |  |  |  |
Impaired loans with a valuation allowance, Interest Income Recognized | 106 | 116 | 188 | 248 |
Impaired loans without a valuation allowance, Interest Income Recognized | 291 | 234 | 625 | 380 |
Impaired loans, Interest Income Recognized | 397 | 350 | 813 | 628 |
Total commercial [Member] |  |  |  |  |
Impaired Financing Receivable, Recorded Investment [Abstract] |  |  |  |  |
Impaired loans, Outstanding Balance | 12,004 |  | 12,004 |  | 9,821
Impaired Financing Receivable, Unpaid Principal Balance [Abstract] |  |  |  |  |
Impaired loans, Unpaid Principal Balance | 12,320 |  | 12,320 |  | 10,137
Impaired loans, Valuation Allowance | 541 |  | 541 |  | 84
Impaired Financing Receivable, Average Recorded Investment [Abstract] |  |  |  |  |
Impaired loans, Average Outstanding Balance | 13,153 | 8,417 | 12,606 | 8,323 |
Impaired Financing Receivable, Interest Income, Accrual Method [Abstract] |  |  |  |  |
Impaired loans, Interest Income Recognized | 174 | 113 | 343 | 218 |
Commercial real estate [Member] |  |  |  |  |
Impaired Financing Receivable, Recorded Investment [Abstract] |  |  |  |  |
Impaired loans with a valuation allowance, Outstanding Balance | 2,556 |  | 2,556 |  | 2,048
Impaired loans without a valuation allowance, Outstanding Balance | 6,004 |  | 6,004 |  | 3,006
Impaired Financing Receivable, Unpaid Principal Balance [Abstract] |  |  |  |  |
Impaired loans with a valuation allowance, Unpaid Principal Balance | 2,556 |  | 2,556 |  | 2,290
Impaired loans without a valuation allowance, Unpaid Principal Balance | 6,320 |  | 6,320 |  | 3,080
Impaired loans, Valuation Allowance | 533 |  | 533 |  | 79
Impaired Financing Receivable, Average Recorded Investment [Abstract] |  |  |  |  |
Impaired loans with a valuation allowance, Average Outstanding Balance | 2,681 | 1,085 | 2,553 | 951 |
Impaired loans without a valuation allowance, Average Outstanding Balance | 6,406 | 4,046 | 5,656 | 4,304 |
Impaired Financing Receivable, Interest Income, Accrual Method [Abstract] |  |  |  |  |
Impaired loans with a valuation allowance, Interest Income Recognized | 35 | 21 | 63 | 46 |
Impaired loans without a valuation allowance, Interest Income Recognized | 93 | 60 | 194 | 119 |
Commercial other [Member] |  |  |  |  |
Impaired Financing Receivable, Recorded Investment [Abstract] |  |  |  |  |
Impaired loans with a valuation allowance, Outstanding Balance | 3,126 |  | 3,126 |  | 107
Impaired loans without a valuation allowance, Outstanding Balance | 318 |  | 318 |  | 4,660
Impaired Financing Receivable, Unpaid Principal Balance [Abstract] |  |  |  |  |
Impaired loans with a valuation allowance, Unpaid Principal Balance | 3,126 |  | 3,126 |  | 107
Impaired loans without a valuation allowance, Unpaid Principal Balance | 318 |  | 318 |  | 4,660
Impaired loans, Valuation Allowance | 8 |  | 8 |  | 5
Impaired Financing Receivable, Average Recorded Investment [Abstract] |  |  |  |  |
Impaired loans with a valuation allowance, Average Outstanding Balance | 1,563 | 460 | 808 | 460 |
Impaired loans without a valuation allowance, Average Outstanding Balance | 2,503 | 2,826 | 3,589 | 2,608 |
Impaired Financing Receivable, Interest Income, Accrual Method [Abstract] |  |  |  |  |
Impaired loans with a valuation allowance, Interest Income Recognized | 36 | 0 | 36 | 6 |
Impaired loans without a valuation allowance, Interest Income Recognized | 10 | 32 | 50 | 47 |
Total agricultural [Member] |  |  |  |  |
Impaired Financing Receivable, Recorded Investment [Abstract] |  |  |  |  |
Impaired loans, Outstanding Balance | 14,843 |  | 14,843 |  | 13,796
Impaired Financing Receivable, Unpaid Principal Balance [Abstract] |  |  |  |  |
Impaired loans, Unpaid Principal Balance | 14,893 |  | 14,893 |  | 13,846
Impaired loans, Valuation Allowance | 3 |  | 3 |  | 56
Impaired Financing Receivable, Average Recorded Investment [Abstract] |  |  |  |  |
Impaired loans, Average Outstanding Balance | 15,152 | 13,426 | 14,890 | 13,839 |
Impaired Financing Receivable, Interest Income, Accrual Method [Abstract] |  |  |  |  |
Impaired loans, Interest Income Recognized | 188 | 189 | 392 | 301 |
Agricultural real estate [Member] |  |  |  |  |
Impaired Financing Receivable, Recorded Investment [Abstract] |  |  |  |  |
Impaired loans with a valuation allowance, Outstanding Balance | 188 |  | 188 |  | 1,994
Impaired loans without a valuation allowance, Outstanding Balance | 9,876 |  | 9,876 |  | 8,681
Impaired Financing Receivable, Unpaid Principal Balance [Abstract] |  |  |  |  |
Impaired loans with a valuation allowance, Unpaid Principal Balance | 238 |  | 238 |  | 1,994
Impaired loans without a valuation allowance, Unpaid Principal Balance | 9,876 |  | 9,876 |  | 8,731
Impaired loans, Valuation Allowance | 3 |  | 3 |  | 54
Impaired Financing Receivable, Average Recorded Investment [Abstract] |  |  |  |  |
Impaired loans with a valuation allowance, Average Outstanding Balance | 607 | 2,224 | 1,058 | 2,051 |
Impaired loans without a valuation allowance, Average Outstanding Balance | 10,016 | 7,441 | 9,717 | 7,612 |
Impaired Financing Receivable, Interest Income, Accrual Method [Abstract] |  |  |  |  |
Impaired loans with a valuation allowance, Interest Income Recognized | 0 | 26 | 11 | 50 |
Impaired loans without a valuation allowance, Interest Income Recognized | 133 | 87 | 265 | 146 |
Agricultural other [Member] |  |  |  |  |
Impaired Financing Receivable, Recorded Investment [Abstract] |  |  |  |  |
Impaired loans with a valuation allowance, Outstanding Balance | 0 |  | 0 |  | 1,355
Impaired loans without a valuation allowance, Outstanding Balance | 4,779 |  | 4,779 |  | 1,766
Impaired Financing Receivable, Unpaid Principal Balance [Abstract] |  |  |  |  |
Impaired loans with a valuation allowance, Unpaid Principal Balance | 0 |  | 0 |  | 1,355
Impaired loans without a valuation allowance, Unpaid Principal Balance | 4,779 |  | 4,779 |  | 1,766
Impaired loans, Valuation Allowance | 0 |  | 0 |  | 2
Impaired Financing Receivable, Average Recorded Investment [Abstract] |  |  |  |  |
Impaired loans with a valuation allowance, Average Outstanding Balance | 0 | 1,355 | 339 | 1,355 |
Impaired loans without a valuation allowance, Average Outstanding Balance | 4,529 | 2,406 | 3,776 | 2,821 |
Impaired Financing Receivable, Interest Income, Accrual Method [Abstract] |  |  |  |  |
Impaired loans with a valuation allowance, Interest Income Recognized | 0 | 20 | 0 | 42 |
Impaired loans without a valuation allowance, Interest Income Recognized | 55 | 56 | 116 | 63 |
Total residential real estate [Member] |  |  |  |  |
Impaired Financing Receivable, Recorded Investment [Abstract] |  |  |  |  |
Impaired loans, Outstanding Balance | 3,688 |  | 3,688 |  | 4,319
Impaired Financing Receivable, Unpaid Principal Balance [Abstract] |  |  |  |  |
Impaired loans, Unpaid Principal Balance | 3,960 |  | 3,960 |  | 4,661
Impaired loans, Valuation Allowance | 657 |  | 657 |  | 771
Impaired Financing Receivable, Average Recorded Investment [Abstract] |  |  |  |  |
Impaired loans, Average Outstanding Balance | 3,912 | 5,151 | 4,070 | 5,291 |
Impaired Financing Receivable, Interest Income, Accrual Method [Abstract] |  |  |  |  |
Impaired loans, Interest Income Recognized | 35 | 48 | 78 | 109 |
Residential real estate senior liens [Member] |  |  |  |  |
Impaired Financing Receivable, Recorded Investment [Abstract] |  |  |  |  |
Impaired loans with a valuation allowance, Outstanding Balance | 3,688 |  | 3,688 |  | 4,319
Impaired Financing Receivable, Unpaid Principal Balance [Abstract] |  |  |  |  |
Impaired loans with a valuation allowance, Unpaid Principal Balance | 3,960 |  | 3,960 |  | 4,661
Impaired loans, Valuation Allowance | 657 |  | 657 |  | $ 771
Impaired Financing Receivable, Average Recorded Investment [Abstract] |  |  |  |  |
Impaired loans with a valuation allowance, Average Outstanding Balance | 3,912 | 5,050 | 4,070 | 5,197 |
Impaired Financing Receivable, Interest Income, Accrual Method [Abstract] |  |  |  |  |
Impaired loans with a valuation allowance, Interest Income Recognized | 35 | 49 | 78 | 104 |
Residential real estate home equity lines of credit [Member] |  |  |  |  |
Impaired Financing Receivable, Average Recorded Investment [Abstract] |  |  |  |  |
Impaired loans without a valuation allowance, Average Outstanding Balance | 0 | 101 | 0 | 94 |
Impaired Financing Receivable, Interest Income, Accrual Method [Abstract] |  |  |  |  |
Impaired loans without a valuation allowance, Interest Income Recognized | 0 | (1) | 0 | 5 |
Total Consumer [Member] |  |  |  |  |
Impaired Financing Receivable, Average Recorded Investment [Abstract] |  |  |  |  |
Impaired loans, Average Outstanding Balance | 0 | 2 | 0 | 2 |
Impaired Financing Receivable, Interest Income, Accrual Method [Abstract] |  |  |  |  |
Impaired loans, Interest Income Recognized | 0 | 0 | 0 | 0 |
Consumer secured [Member] |  |  |  |  |
Impaired Financing Receivable, Average Recorded Investment [Abstract] |  |  |  |  |
Impaired loans without a valuation allowance, Average Outstanding Balance | 0 | 2 | 0 | 2 |
Impaired Financing Receivable, Interest Income, Accrual Method [Abstract] |  |  |  |  |
Impaired loans without a valuation allowance, Interest Income Recognized | $ 0 | $ 0 | $ 0 | $ 0 |

X
- Definition Average amount of investment of impaired financing receivables with related allowance for credit losses and without 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=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 http://asc.fasb.org/extlink&oid=123577603&loc=d3e5258-111524 + Details
Name: | us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- References No definition available. + Details
Name: | us-gaap_ImpairedFinancingReceivableAverageRecordedInvestmentAbstract
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount of interest income recognized that the financing receivables (with related allowance for credit losses and without a related allowance for credit losses) were 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=123577603&loc=d3e5212-111524 + Details
Name: | us-gaap_ImpairedFinancingReceivableInterestIncomeAccrualMethod
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- References No definition available. + Details
Name: | us-gaap_ImpairedFinancingReceivableInterestIncomeAccrualMethodAbstract
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount of investment of impaired financing receivables with related allowance for credit losses and without 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 14A -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=123577603&loc=SL6953550-111524 + Details
Name: | us-gaap_ImpairedFinancingReceivableRecordedInvestment
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- References No definition available. + Details
Name: | us-gaap_ImpairedFinancingReceivableRecordedInvestmentAbstract
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount of allowance for credit losses related to recorded investment. + 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 (a)(3) -URI http://asc.fasb.org/extlink&oid=123577603&loc=d3e5212-111524 + Details
Name: | us-gaap_ImpairedFinancingReceivableRelatedAllowance
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Amount of unpaid principal balance of impaired financing receivables with related allowance for credit losses and without 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 (a)(4) -URI http://asc.fasb.org/extlink&oid=123577603&loc=d3e5212-111524 + Details
Name: | us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- References No definition available. + Details
Name: | us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalanceAbstract
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount of average investment of impaired financing receivables for which there is no 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 17 -URI http://asc.fasb.org/extlink&oid=123577603&loc=d3e5258-111524 Reference 2: 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=123577603&loc=d3e5212-111524 + Details
Name: | us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceAverageRecordedInvestment
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 that are recognized as impaired, for which there is no 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)(2) -URI http://asc.fasb.org/extlink&oid=123577603&loc=d3e5212-111524 + Details
Name: | us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceInterestIncomeAccrualMethod
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Amount of investment in impaired financing receivables for which there is no 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 14A -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=123577603&loc=SL6953550-111524 + Details
Name: | us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceRecordedInvestment
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount of unpaid principal balance of impaired financing receivables for which there is no 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 (a)(4) -URI http://asc.fasb.org/extlink&oid=123577603&loc=d3e5212-111524 + Details
Name: | us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceUnpaidPrincipalBalance
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

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=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 http://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 http://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
- Definition Amount of investment in 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 14A -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=123577603&loc=SL6953550-111524 + Details
Name: | us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceRecordedInvestment
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Unpaid principal balance 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 (a)(4) -URI http://asc.fasb.org/extlink&oid=123577603&loc=d3e5212-111524 + Details
Name: | us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceUnpaidPrincipalBalance
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

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

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

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

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

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