Note 6 - Goodwill (Details) - Goodwill (USD $) In Thousands, unless otherwise specified	3 Months Ended	12 Months Ended
	Aug. 31, 2013	May 31, 2013
Goodwill [Line Items]
Balance at beginning of period	$ 1,003,463	$ 966,338
Foreign currency translation adjustment	326	236
Balance at end of period	1,003,789	1,003,463
LIFECODES [Member]
Goodwill [Line Items]
Acquisition of LIFECODES		$ 36,889