| Document And Entity Information | Apr. 22, 2021 |
| Document Information [Line Items] | |
| Entity, Registrant Name | LSI INDUSTRIES INC. |
| Document, Type | 8-K |
| Document, Period End Date | Apr. 22, 2021 |
| Entity, Incorporation, State or Country Code | OH |
| Entity, File Number | 01-13375 |
| Entity, Tax Identification Number | 31-0888951 |
| Entity, Address, Address Line One | 10000 Alliance Road |
| Entity, Address, City or Town | Cincinnati |
| Entity, Address, State or Province | OH |
| Entity, Address, Postal Zip Code | 45242 |
| City Area Code | 513 |
| Local Phone Number | 793-3200 |
| Written Communications | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Title of 12(b) Security | Common Stock |
| Trading Symbol | LYTS |
| Security Exchange Name | NASDAQ |
| Entity, Emerging Growth Company | false |
| Amendment Flag | false |
| Entity, Central Index Key | 0000763532 |
