Note 12 - Fair Value (Details) - Assets and Liabilities Measured at Fair Value on a Recurring Basis - USD ($) $ in Thousands	Aug. 31, 2015	May. 31, 2015	May. 31, 2014
Note 12 - Fair Value (Details) - Assets and Liabilities Measured at Fair Value on a Recurring Basis [Line Items]
Derivative instruments	$ (506)	$ (686)
Contingent consideration liability	(18,863)	(18,596)	$ (11,300)
Fair Value, Inputs, Level 2 [Member]
Note 12 - Fair Value (Details) - Assets and Liabilities Measured at Fair Value on a Recurring Basis [Line Items]
Derivative instruments	(506)	(686)
Fair Value, Inputs, Level 3 [Member]
Note 12 - Fair Value (Details) - Assets and Liabilities Measured at Fair Value on a Recurring Basis [Line Items]
Contingent consideration liability	$ (18,863)	$ (18,596)