XML 67 R61.htm IDEA: XBRL DOCUMENT
v3.25.3

Disclosures About Fair Value of Assets - Quantitative Information about Unobservable Inputs Used in Recurring and Nonrecurring Level 3 Fair Value Measurements (Detail) $ in Thousands | 3 Months Ended | 12 Months Ended |
--- | --- | --- | ---
Sep. 30, 2025 USD ($) mo yr | Jun. 30, 2024 USD ($) | Jun. 30, 2025 USD ($) mo yr
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items] |  |  |
Mortgage servicing rights | $ 1,430 |  | $ 1,429
State and political subdivisions | 1,748 | $ 1,748 |
Foreclosed assets | $ 40 |  |
Discount Rate [Member] | Discounted Cash Flow [Member] |  |  |
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items] |  |  |
Mortgage servicing rights, measurement input | 9.5 |  | 9.5
Comparability Adjustments [Member] | Market Comparable Properties [Member] |  |  |
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items] |  |  |
Mortgage servicing rights, measurement input | 0 |  |
Minimum [Member] | Constant Prepayment Rate [Member] | Discounted Cash Flow [Member] |  |  |
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items] |  |  |
Mortgage servicing rights, measurement input | 5 |  | 4.9
Minimum [Member] | Probability of Default [Member] | Discounted Cash Flow [Member] |  |  |
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items] |  |  |
Mortgage servicing rights, measurement input | 0.07 |  | 0.07
Minimum [Member] | Maturity/Call Date [Member] | Discounted Cash Flow [Member] |  |  |
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items] |  |  |
Mortgage servicing rights, measurement input | mo | 1 |  | 1
Minimum [Member] | Weighted average coupon [Member] | Discounted Cash Flow [Member] |  |  |
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items] |  |  |
Mortgage servicing rights, measurement input | 2.97 |  | 2.97
Minimum [Member] | Marketability yield adjustment [Member] | Discounted Cash Flow [Member] |  |  |
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items] |  |  |
Mortgage servicing rights, measurement input | 1 |  | 1
Maximum [Member] | Constant Prepayment Rate [Member] | Discounted Cash Flow [Member] |  |  |
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items] |  |  |
Mortgage servicing rights, measurement input | 11.1 |  | 9.8
Maximum [Member] | Probability of Default [Member] | Discounted Cash Flow [Member] |  |  |
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items] |  |  |
Mortgage servicing rights, measurement input | 0.12 |  | 0.12
Maximum [Member] | Maturity/Call Date [Member] | Discounted Cash Flow [Member] |  |  |
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items] |  |  |
Mortgage servicing rights, measurement input | yr | 6 |  | 6
Maximum [Member] | Weighted average coupon [Member] | Discounted Cash Flow [Member] |  |  |
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items] |  |  |
Mortgage servicing rights, measurement input | 3.08 |  | 3.08
Maximum [Member] | Marketability yield adjustment [Member] | Discounted Cash Flow [Member] |  |  |
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items] |  |  |
Mortgage servicing rights, measurement input | 2 |  | 2
Weighted Average [Member] | Constant Prepayment Rate [Member] | Discounted Cash Flow [Member] |  |  |
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items] |  |  |
Mortgage servicing rights, measurement input | 10.3 |  | 9.2
Weighted Average [Member] | Probability of Default [Member] | Discounted Cash Flow [Member] |  |  |
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items] |  |  |
Mortgage servicing rights, measurement input | 0.12 |  | 0.12
Weighted Average [Member] | Weighted average coupon [Member] | Discounted Cash Flow [Member] |  |  |
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items] |  |  |
Mortgage servicing rights, measurement input | 3.04 |  | 3.04
Weighted Average [Member] | Marketability yield adjustment [Member] | Discounted Cash Flow [Member] |  |  |
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items] |  |  |
Mortgage servicing rights, measurement input | 1.6 |  | 1.6

X
- Definition Foreclosed assets fair value disclosure. + References No definition available. + Details
Name: | iroq_ForeclosedAssetsFairValueDisclosure
Namespace Prefix: | iroq_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Impaired loans gain losses recognized on assets fair value disclosure. + References No definition available. + Details
Name: | iroq_ImpairedLoansGainLossesRecognizedOnAssetsFairValueDisclosure
Namespace Prefix: | iroq_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Mortgage servicing rights fair value disclosure. + References No definition available. + Details
Name: | iroq_MortgageServicingRightsFairValueDisclosure
Namespace Prefix: | iroq_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Mortgage servicing rights measurement input. + References No definition available. + Details
Name: | iroq_MortgageServicingRightsMeasurementInput
Namespace Prefix: | iroq_
Data Type: | xbrli:decimalItemType
Balance Type: | na
Period Type: | instant

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/disclosureRef -Topic 825 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 11 -Subparagraph (a) -Publisher FASB -URI https://asc.fasb.org/1943274/2147482907/825-10-50-11 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Topic 942 -SubTopic 825 -Name Accounting Standards Codification -Section 50 -Paragraph 1 -Subparagraph (a) -Publisher FASB -URI https://asc.fasb.org/1943274/2147478898/942-825-50-1 + Details
Name: | us-gaap_FairValueOffBalanceSheetRisksDisclosureInformationLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | us-gaap_MeasurementInputTypeAxis=us-gaap_MeasurementInputDiscountRateMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

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

X
- Details
Name: | us-gaap_MeasurementInputTypeAxis=us-gaap_MeasurementInputComparabilityAdjustmentMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

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

X
- Details
Name: | srt_RangeAxis=srt_MinimumMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_MeasurementInputTypeAxis=us-gaap_MeasurementInputConstantPrepaymentRateMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_MeasurementInputTypeAxis=us-gaap_MeasurementInputDefaultRateMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_MeasurementInputTypeAxis=iroq_MaturityCallDateMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_MeasurementInputTypeAxis=iroq_WeightedAverageCouponMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_MeasurementInputTypeAxis=iroq_MarketabilityYieldAdjustmentMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_RangeAxis=srt_MaximumMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_RangeAxis=srt_WeightedAverageMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |