Note 16 - Contingent Consideration Liability (Details) - USD ($) $ in Thousands	12 Months Ended
	May 31, 2016	May 31, 2015	May 31, 2014
Balance	$ 18,596	$ 11,300
Additions due to acquisitions	(20,000)	(6,469)	$ (11,300)
Payments	65	87
Accretion of fair value	(1,825)	(914)
Balance	$ (40,356)	$ (18,596)	$ (11,300)