Note 3 - Segment Reporting Information - Intersegment Revenues (Details) - USD ($) $ in Thousands	3 Months Ended
Sep. 30, 2019	Sep. 30, 2018
Inter-segment Revenues	$ 88,701	$ 84,957
Lighting Segment [Member]
Inter-segment Revenues	63,191	61,432
Graphics Segment [Member]
Inter-segment Revenues	25,510	23,525
Intersegment Eliminations [Member] \| Lighting Segment [Member]
Inter-segment Revenues	811	409
Intersegment Eliminations [Member] \| Graphics Segment [Member]
Inter-segment Revenues	$ 24	$ 31

Amount, including tax collected from customer, of revenue from satisfaction of performance obligation by transferring promised good or service to customer. Tax collected from customer is tax assessed by governmental authority that is both imposed on and concurrent with specific revenue-producing transaction, including, but not limited to, sales, use, value-added and excise.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=118956577&loc=SL49130545-203045

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 4
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=118956577&loc=SL49130543-203045

Name:	us-gaap_RevenueFromContractWithCustomerIncludingAssessedTax
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration