Note 16 - Segment and Geographic Information (Details) - Sales by Product Group - USD ($) $ in Thousands	3 Months Ended
Aug. 31, 2015	Aug. 31, 2014
Net sales by product group:
Net sales by product group	$ 96,712	$ 102,441
Transfusion [Member]
Net sales by product group:
Net sales by product group	81,156	86,369
Transplant & Molecular [Member]
Net sales by product group:
Net sales by product group	$ 15,556	$ 16,072

Total revenue from sale of goods and services rendered during the reporting period, in the normal course of business, reduced by sales returns and allowances, and sales discounts.

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=26872669&loc=d3e20235-122688

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