Cover Page - shares	6 Months Ended
	Dec. 31, 2019	Feb. 03, 2020
Cover [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Dec. 31, 2019
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	Q2
Trading Symbol	IROQ
Entity Registrant Name	IF Bancorp, Inc.
Entity Central Index Key	0001514743
Current Fiscal Year End Date	--06-30
Entity Current Reporting Status	Yes
Entity Filer Category	Non-accelerated Filer
Entity Common Stock, Shares Outstanding		3,260,171
Entity Interactive Data Current	Yes
Entity Shell Company	false
Entity Small Business	true
Entity Emerging Growth Company	false
Title of 12(b) Security	Common Stock
Security Exchange Name	NASDAQ
Entity Address, State or Province	IL