Note 2 - Business Segment Information - Intersegment Revenues (Details) - USD ($) $ in Thousands	3 Months Ended												12 Months Ended
	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2017		Jun. 30, 2016		Jun. 30, 2015		Jun. 30, 2014	Jun. 30, 2013
Inter-segment Revenues	$ 83,419	$ 78,156	$ 85,658	$ 84,159	$ 80,844	$ 70,740	$ 84,687	$ 85,925	$ 76,073	$ 68,603	$ 84,715	$ 78,466	$ 331,392	[1]	$ 322,196	[1]	$ 307,857	[1]	$ 299,463	$ 280,790
Lighting Segment [Member]
Inter-segment Revenues													239,005		226,889		219,920
Graphics Segment [Member]
Inter-segment Revenues													72,395		77,968		67,152
Technology Segment [Member]
Inter-segment Revenues													19,992		17,339		20,744
Other Segments [Member]
Inter-segment Revenues																	41
Intersegment Eliminations [Member] | Lighting Segment [Member]
Inter-segment Revenues													2,559		2,935		2,752
Intersegment Eliminations [Member] | Graphics Segment [Member]
Inter-segment Revenues													1,135		1,760		559
Intersegment Eliminations [Member] | Technology Segment [Member]
Inter-segment Revenues													33,981		35,733		29,412
Intersegment Eliminations [Member] | Other Segments [Member]
Inter-segment Revenues																	$ 308

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