Document And Entity Information - shares	6 Months Ended
	Dec. 31, 2018	Jan. 27, 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 Emerging Growth Company	false
Entity Small Business	false
Entity Common Stock, Shares Outstanding (in shares)		25,888,975
Document Type	10-Q
Document Period End Date	Dec. 31, 2018
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	Q2
Amendment Flag	false