Note 11 - Fair Value (Details Textual) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Feb. 28, 2017	May 31, 2016	Feb. 29, 2016	May 31, 2015
Cash and Cash Equivalents, at Carrying Value	$ 10,035	$ 10,263	$ 12,190	$ 18,363
Business Combination, Contingent Consideration, Liability	43,384	40,356		$ 18,596
Contingent Consideration [Member]
Business Combination, Contingent Consideration, Liability	43,400	40,400
Term Loan Facility [Member]
Long-term Debt, Fair Value	631,200	614,500
Notes Payable, Other Payables [Member]
Long-term Debt, Fair Value	$ 384,000	$ 364,300
Geographic Concentration Risk [Member] | UNITED STATES | Cash and Cash Equivalents1 [Member]
Concentration Risk, Percentage	42.00%	38.00%