Note 16 - Long-term Debt (Details Textual) - USD ($) $ in Thousands		3 Months Ended		6 Months Ended
	Mar. 17, 2017	Feb. 28, 2018	Feb. 28, 2017	Feb. 28, 2018	Feb. 28, 2017	Aug. 31, 2017
Interest Paid		$ 3,600	$ 1,300	$ 7,000	$ 2,400
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
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%