Note 19 - Unrecognized Tax Benefits (Details) - USD ($) $ in Thousands	12 Months Ended
	May 31, 2016	May 31, 2015
Balance, beginning of period	$ 12,467	$ 12,863
Gross increases(decreases) in unrecognized tax benefits as a result of tax positions taken during a prior period	4,925	(337)
Gross increases(decreases) in unrecognized tax benefits as a result of tax positions taken during current period	1,100	1,180
Reductions to unrecognized tax benefits as a result of the applicable statute of limitations		(1,239)
Balance, end of period	$ 18,680	$ 12,467