Note 11 - Derivative Financial Instruments (Details) - Fair Values of the Interest Rate Swap Agreements - USD ($) $ in Thousands	Aug. 31, 2015	May. 31, 2015
Fair Values of the Interest Rate Swap Agreements [Abstract]
Interest rate swaps (included in other liabilities)	$ (506)	$ (686)

Fair value as of the balance sheet date of interest rate derivative liabilities, which includes all such derivative instruments in hedging and nonhedging relationships that are recognized as liabilities.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 825

-SubTopic 10

-Section 50

-Paragraph 10

-Subparagraph (a)

-URI http://asc.fasb.org/extlink&oid=49121117&loc=d3e13433-108611

Name:	us-gaap_InterestRateDerivativeLiabilitiesAtFairValue
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant