Note 2 - Business Segment Information (Details) - Inter-segment Revenues - USD ($) $ in Thousands	3 Months Ended												12 Months Ended
	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2015		Jun. 30, 2014		Jun. 30, 2013		Jun. 30, 2012	Jun. 30, 2011
Segment Reporting, Revenue Reconciling Item [Line Items]
Net sales	$ 76,073	$ 68,603	$ 84,715	$ 78,466	$ 73,858	$ 68,996	$ 76,123	$ 80,486	$ 68,837	$ 66,152	$ 71,082	$ 74,719	$ 307,857	[1]	$ 299,463	[1]	$ 280,790	[1]	$ 268,402	$ 293,501
Lighting Segment [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Net sales													219,920		222,604		200,335
Lighting Segment [Member] | Intersegment Eliminations [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Net sales													2,752		3,534		2,746
Graphics Segment [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Net sales													64,895		50,970		53,122
Graphics Segment [Member] | Intersegment Eliminations [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Net sales													559		1,088		961
Technology Segment [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Net sales													23,001		24,515		26,361
Technology Segment [Member] | Intersegment Eliminations [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Net sales													29,412		34,238		26,522
All Other Category [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Net sales													41		1,374		972
All Other Category [Member] | Intersegment Eliminations [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Net sales													$ 308		$ 2,286		$ 2,843

[1] Net sales are attributed to geographic areas based upon the location of the operation making the sale.