Note 16 - Income Taxes (Details Textual) - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2021	Mar. 31, 2020
Income Tax Benefit Cares Act	$ 0.4	$ 0.3

Amount of income tax benefit related to the CARES Act.

No definition available.

Name:	lyts_IncomeTaxBenefitCaresAct
Namespace Prefix:	lyts_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration