Note 10 - Derivative Financial Instruments - The Loss From Accumulated Other Comprehensive Income (Loss) (OCI) Into Income (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Feb. 28, 2017	Feb. 29, 2016	Feb. 28, 2017	Feb. 28, 2016
Interest expense (effective portion)		$ (121)	$ (167)	$ (489)
Interest Income [Member]
Interest expense (ineffective portion)				$ (1)

The portion of gains and losses (net) on derivative instruments designated and qualifying as hedging instruments representing (a) the amount of the hedge ineffectiveness and (b) the amount, if any, excluded from the assessment of hedge effectiveness.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4C
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=64837297&loc=SL5624171-113959

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 25
-Section 50
-Paragraph 1
-Subparagraph (a)(1),(2)
-URI http://asc.fasb.org/extlink&oid=6886632&loc=d3e76258-113986

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