Note 7 - Goodwill (Details) - Changes in Goodwill - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Aug. 31, 2015	May. 31, 2015
Changes in Goodwill [Abstract]
Balance at beginning of period	$ 842,258	$ 851,563
Additions:
Acquisition of businesses	346	432
Foreign currency translation adjustment	(294)	(9,737)
Balance at end of period	$ 842,310	$ 842,258