Note 10 - Business Segment Reporting - Sales by Geographic Area (Details) - USD ($) $ in Millions	3 Months Ended
Aug. 28, 2016	Aug. 30, 2015
CANADA
Segment sales	$ 17.8	$ 20.7
TAIWAN, PROVINCE OF CHINA
Segment sales	13.7	13.0
BELGIUM
Segment sales	5.3	0.8
CHINA
Segment sales	5.2	4.0
JAPAN
Segment sales	2.0	2.0
INDONESIA
Segment sales	1.5	1.5
All Other Countries [Member]
Segment sales	$ 2.7	$ 4.3

Amount of revenue recognized from goods sold, services rendered, insurance premiums, or other activities that constitute an earning process. Includes, but is not limited to, investment and interest income before deduction of interest expense when recognized as a component of revenue, and sales and trading gain (loss).

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 225
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03.1)
-URI http://asc.fasb.org/extlink&oid=63488584&loc=d3e20235-122688

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration