Interest-Bearing Deposits - Interest Expense by Deposit Type (Detail) - USD ($) $ in Thousands	12 Months Ended
Jun. 30, 2016	Jun. 30, 2015
Banking and Thrift [Abstract]
Savings, NOW, and Money Market	$ 226	$ 208
Certificates of deposit	1,778	2,044
Brokered certificates of deposit	371	181
Total deposit interest expense	$ 2,375	$ 2,433

Interest expense deposit type brokered certificates of deposit.

No definition available.

Name:	iroq_InterestExpenseDepositTypeBrokeredCertificatesOfDeposit
Namespace Prefix:	iroq_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- References

No definition available.

+ Details

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

- Definition

Aggregate amount of interest expense on all deposits.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 225
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-04.6)
-URI http://asc.fasb.org/extlink&oid=6879574&loc=d3e536633-122882

+ Details

Name:	us-gaap_InterestExpenseDeposits
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The aggregate interest expense incurred on the following for deposits in domestic offices: (1) transaction accounts (NOW, and telephone and preauthorized transfer accounts), (2) money market deposits and (3) savings deposits.

+ References

+ Details

Name:	us-gaap_InterestExpenseNOWAccountsMoneyMarketAccountsAndSavingsDeposits
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The aggregate interest expense incurred on time deposits, including certificates of deposits, in domestic offices.

+ References

+ Details

Name:	us-gaap_InterestExpenseTimeDeposits
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration