Note 10 - Long-term Debt (Details) - Interest Expense (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended		12 Months Ended
	Feb. 28, 2015	Feb. 28, 2014	Feb. 28, 2015	Feb. 28, 2014	May 31, 2014
Note 10 - Long-term Debt (Details) - Interest Expense [Line Items]
Amortization of deferred financing costs	$ 1,674	$ 1,577	$ 4,998	$ 4,713
Interest rate swaps	209	246	700	766
Revolving Facility fees and interest	157	125	516	379
Interest accreted on contingent consideration liabilities	(158)		642	140	134
Interest expense	21,793	21,900	66,913	66,172
Notes Payable, Other Payables [Member]
Note 10 - Long-term Debt (Details) - Interest Expense [Line Items]
Interest expense including OID amortization	11,265	11,250	33,792	33,747
Term Loan Facility [Member]
Note 10 - Long-term Debt (Details) - Interest Expense [Line Items]
Interest expense including OID amortization	$ 8,646	$ 8,702	$ 26,265	$ 26,427