Note 7 - Goodwill and Other Intangible Assets - Goodwill (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Jun. 30, 2017
Goodwill, net	$ 30,538,000		$ 30,538,000		$ 58,538,000
Total Gains (Losses)	(28,000,000)		(28,000,000)
Lighting Segment [Member]
Goodwill	94,564,000		94,564,000		94,564,000
Accumulated impairment losses	(65,191,000)		(65,191,000)		(37,191,000)
Goodwill, net	29,373,000		29,373,000		57,373,000
Total Gains (Losses)	(28,000,000)
Graphics Segment [Member]
Goodwill	28,690,000		28,690,000		28,690,000
Accumulated impairment losses	(27,525,000)		(27,525,000)		(27,525,000)
Goodwill, net	1,165,000		1,165,000		1,165,000
Total Gains (Losses)
Technology Segment [Member]
Goodwill	123,254,000		123,254,000		123,254,000
Accumulated impairment losses	(92,716,000)		(92,716,000)		(64,716,000)
Goodwill, net	30,538,000		$ 30,538,000		$ 58,538,000
Total Gains (Losses)	$ (28,000,000)