Note 2 - Business Combinations (Details) - Pro Forma Financial Information (USD $) In Thousands, unless otherwise specified	12 Months Ended
May 31, 2013 LIFECODES [Member]	May 31, 2012 LIFECODES [Member]	May 31, 2012 Immucor Inc [Member]	May 31, 2011 Immucor Inc [Member]
Note 2 - Business Combinations (Details) - Pro Forma Financial Information [Line Items]
Net sales	$ 385,916	$ 382,368	$ 336,724	$ 333,091
Net loss	$ (39,326)	$ (61,121)	$ (55,140)	$ (3,858)

The pro forma net Income or Loss for the period as if the business combination or combinations had been completed at the beginning of a period.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 805

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (h)(2)-(3)

-URI http://asc.fasb.org/extlink&oid=25497992&loc=d3e1392-128463

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