Note 6 - Goodwill (Details) - Goodwill (USD $) In Thousands, unless otherwise specified	9 Months Ended	12 Months Ended
	Feb. 28, 2014	May 31, 2013
Goodwill [Line Items]
Balance at beginning of period	$ 1,003,463	$ 966,338
Foreign currency translation adjustment	1,226	236
Balance at end of period	1,005,778	1,003,463
LIFECODES [Member]
Goodwill [Line Items]
Acquisition of businesses	1,089	36,889
Balance at end of period	$ 1,100