Employee Benefits - Benefit Payments Expected to be Paid for Agreements (Detail) $ in Thousands	Jun. 30, 2025 USD ($)
Defined Benefit Plan Disclosure [Line Items]
2026	$ 129
2027	156
2028	182
2029	193
2030	203
Thereafter	875
Deferred Compensation Agreements [Member]
Defined Benefit Plan Disclosure [Line Items]
2026	199
2027	240
2028	262
2029	292
2030	300
Thereafter	4,489
Total	$ 5,782

Defined benefit plan expected future benefit payments.

No definition available.

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Namespace Prefix:	iroq_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
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- 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

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Namespace Prefix:	us-gaap_
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Balance Type:	na
Period Type:	duration

- Definition

Amount of benefit for defined benefit plan expected to be paid in five fiscal years after fifth fiscal year following current fiscal year.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 715
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (f)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480506/715-20-50-1

+ Details

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- Definition

Amount of benefit for defined benefit plan expected to be paid in next fiscal year following current fiscal year.

+ References

+ Details

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Namespace Prefix:	us-gaap_
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- Definition

Amount of benefit for defined benefit plan expected to be paid in fifth fiscal year following current fiscal year.

+ References

+ Details

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Namespace Prefix:	us-gaap_
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- Definition

Amount of benefit for defined benefit plan expected to be paid in fourth fiscal year following current fiscal year.

+ References

+ Details

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Period Type:	instant

- Definition

Amount of benefit for defined benefit plan expected to be paid in third fiscal year following current fiscal year.

+ References

+ Details

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- Definition

Amount of benefit for defined benefit plan expected to be paid in second fiscal year following current fiscal year.

+ References

+ Details

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- Details

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