Note 17 - Long-term Debt (Details Textual) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
	Mar. 17, 2017	May 31, 2017	May 31, 2016	May 31, 2017	May 31, 2016
Interest Paid		$ 2,900	$ 900	$ 5,300	$ 2,200
Payments of Debt Issuance Costs				437	$ 12
The 2017 Revolving Credit Facility [Member] | PNC Bank, National Associations [Member]
Line of Credit Facility, Maximum Borrowing Capacity	$ 575,000
Line of Credit Facility, Maximum Amount Of Additional Borrowings	225,000
Line of Credit Facility, Minimum Borrowing Amount Required for Additional Borrowings	$ 25,000
Long-term Line of Credit		$ 575,000		575,000
Payments of Debt Issuance Costs				400
Line of Credit Facility, Commitment Fee Amount				$ 0
The 2017 Revolving Credit Facility [Member] | PNC Bank, National Associations [Member] | London Interbank Offered Rate (LIBOR) [Member]
Debt Instrument, Basis Spread on Variable Rate	1.00%
The 2015 Revolving Credit Facility [Member] | Bank of America, N.A. [Member]
Extinguishment of Debt, Amount	$ 365,000