Debt (Schedule Of Long-Term Debt) (Details) - USD ($) $ in Thousands	Aug. 31, 2018	Aug. 31, 2017
Debt Instrument [Line Items]
Total long-term debt	$ 717,396	$ 637,521
Less unamortized debt issuance costs	(11,668)	(9,405)
Less long-term debt due within one year	(4,250)	0
Long-term debt, net	701,478	628,116
Class A-2 2018 Fixed Rate Notes [Member]
Debt Instrument [Line Items]
Total long-term debt	170,000	0
Class A-2 2016 Fixed Rate Notes [Member]
Debt Instrument [Line Items]
Total long-term debt	399,911	422,521
Class A-1 2016 Variable Funding Notes [Member]
Debt Instrument [Line Items]
Total long-term debt	0	60,000
Class A-2 2013 Fixed Rate Notes [Member]
Debt Instrument [Line Items]
Total long-term debt	$ 147,485	$ 155,000