Note 2 - Business Segment Information - Summarized Financial Information by Reportable Business Segments (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
Net Sales:
Net sales	$ 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
Operating Income (Loss):
Operating income (loss)													3,609		13,956		7,533		$ 2,318	$ 630
Capital Expenditures:
Capital expenditures													6,633		10,211		4,754
Depreciation and Amortization:
Depreciation and amortization													8,262		6,677		6,331
Corporate and Eliminations [Member]
Operating Income (Loss):
Operating income (loss)													(13,281)		(11,103)		(11,164)
Capital Expenditures:
Capital expenditures													636		416		599
Depreciation and Amortization:
Depreciation and amortization													1,139		1,214		1,015
Lighting Segment [Member]
Net Sales:
Net sales													239,005		226,889		219,920
Lighting Segment [Member] | Operating Segments [Member]
Operating Income (Loss):
Operating income (loss)													10,566		15,785		14,775
Capital Expenditures:
Capital expenditures													4,010		4,255		1,905
Depreciation and Amortization:
Depreciation and amortization													4,337		2,930		2,965
Graphics Segment [Member]
Net Sales:
Net sales													72,395		77,968		67,152
Graphics Segment [Member] | Operating Segments [Member]
Operating Income (Loss):
Operating income (loss)													2,439		5,246		952
Capital Expenditures:
Capital expenditures													1,748		3,688		1,105
Depreciation and Amortization:
Depreciation and amortization													1,474		1,104		1,042
Technology Segment [Member]
Net Sales:
Net sales													19,992		17,339		20,744
Technology Segment [Member] | Operating Segments [Member]
Operating Income (Loss):
Operating income (loss)													3,885		4,028		3,153
Capital Expenditures:
Capital expenditures													239		1,852		1,141
Depreciation and Amortization:
Depreciation and amortization													1,312		1,429		1,278
Other Segments [Member]
Net Sales:
Net sales																	41
Other Segments [Member] | Operating Segments [Member]
Operating Income (Loss):
Operating income (loss)																	(183)
Capital Expenditures:
Capital expenditures																	4
Depreciation and Amortization:
Depreciation and amortization																	$ 31

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