Document And Entity Information - USD ($)	12 Months Ended
	Jun. 30, 2020	Aug. 31, 2020	Dec. 31, 2019
Document Information [Line Items]
Entity Registrant Name	LSI INDUSTRIES INC
Entity Central Index Key	0000763532
Trading Symbol	lyts
Current Fiscal Year End Date	--06-30
Entity Filer Category	Accelerated Filer
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Entity Well-known Seasoned Issuer	No
Entity Emerging Growth Company	false
Entity Small Business	true
Entity Interactive Data Current	Yes
Entity Common Stock, Shares Outstanding (in shares)		26,331,777
Entity Public Float			$ 153,525,829
Entity Shell Company	false
Document Type	10-K
Document Period End Date	Jun. 30, 2020
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	FY
Amendment Flag	false
Title of 12(b) Security	Common shares, no par value