Note 11 - Interest Expense (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Feb. 29, 2016	Feb. 28, 2015	Feb. 29, 2016	Feb. 28, 2015
Notes Payable, Other Payables [Member]
Interest Expense Including OID Amortization	$ 11,285	$ 11,265	$ 33,847	$ 33,792
Term Loan Facility [Member]
Interest Expense Including OID Amortization	8,685	8,646	26,190	26,265
Amortization of deferred financing costs	1,792	1,674	5,327	4,998
Interest rate swaps and other interest	122	209	487	700
Revolving facility fees and interest	154	157	563	516
Interest accreted on contingent consideration liabilities	291	(158)	861	642
Interest expense	$ 22,329	$ 21,793	$ 67,275	$ 66,913