XML 94 R83.htm IDEA: XBRL DOCUMENT v3.20.2

Regulatory Matters - Additional Information (Detail) - USD ($) $ in Billions	Jan. 01, 2019	Jun. 30, 2020	Mar. 31, 2020
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Maximum Asset Value Required To Be Maintained Leverage Ratio		$ 10
Capital conservation buffer risk-weighted assets	2.50%
Covid 19[Member] | Throughout Two Thousand And Twenty [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Leverage ratio		8.00%
Covid 19[Member] | Throughout Two Thousand And Twenty One [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Leverage ratio		8.50%
Covid 19[Member] | From Two Thousand And Twenty Two Onwards [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Leverage ratio		9.00%
Maximum [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Leverage ratio			9.00%

X

- Definition

Maximum Asset Value Required To Be Maintained Leverage Ratio.

+ References

No definition available.

+ Details

Name:	iroq_MaximumAssetValueRequiredToBeMaintainedLeverageRatio
Namespace Prefix:	iroq_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

X

- Definition

Tier one risk based capital to risk weighted assets conservation buffer.

+ References

No definition available.

+ Details

Name:	iroq_TierOneRiskBasedCapitalToRiskWeightedAssetsConservationBuffer
Namespace Prefix:	iroq_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

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_ComplianceWithRegulatoryCapitalRequirementsUnderBankingRegulationsLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

X

- Definition

Tier 1 Leverage Capital divided by average assets as defined in the regulations.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 505
-Section 50
-Paragraph 1
-Subparagraph (c)(1)
-URI http://asc.fasb.org/extlink&oid=117337116&loc=SL5958568-112826

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 505
-Section 50
-Paragraph 1H
-Subparagraph (c)(2)
-URI http://asc.fasb.org/extlink&oid=117337116&loc=d3e65071-112826

+ Details

Name:	us-gaap_TierOneLeverageCapitalToAverageAssets
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

X

- Details

Name:	iroq_UnexpectedEventAxis=iroq_CovidNineteenMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	iroq_CommunityBankLeverageRatioPeriodAxis=iroq_ThroughoutTwoThousandAndTwentyMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	iroq_CommunityBankLeverageRatioPeriodAxis=iroq_ThroughoutTwoThousandAndTwentyOneMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	iroq_CommunityBankLeverageRatioPeriodAxis=iroq_FromTwoThousandAndTwentyTwoOnwardsMember
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: