Property, Equipment And Capital Leases (Schedule Of Property, Equipment And Capital Leases) (Details) - USD ($) $ in Thousands	12 Months Ended
	Aug. 31, 2018	Aug. 31, 2017
Property, Plant and Equipment [Line Items]
Property and equipment, at cost	$ 559,485	$ 570,686
Accumulated depreciation	(271,940)	(272,233)
Property and equipment, net	287,545	298,453
Capital leases	39,204	45,315
Accumulated amortization	(28,527)	(31,388)
Capital leases, net	10,677	13,927
Property, equipment and capital leases, net	298,222	312,380
Land [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, at cost	120,352	117,402
Buildings And Improvements [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, at cost	243,434	251,695
Drive-In Equipment [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, at cost	62,679	75,410
Brand Technology Development And Other Equipment [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, at cost	$ 133,020	$ 126,179
Minimum [Member] | Buildings And Improvements [Member]
Property, Plant and Equipment [Line Items]
Estimated useful life	8 years
Minimum [Member] | Drive-In Equipment [Member]
Property, Plant and Equipment [Line Items]
Estimated useful life	5 years
Minimum [Member] | Brand Technology Development And Other Equipment [Member]
Property, Plant and Equipment [Line Items]
Estimated useful life	2 years
Maximum [Member] | Buildings And Improvements [Member]
Property, Plant and Equipment [Line Items]
Estimated useful life	25 years
Maximum [Member] | Drive-In Equipment [Member]
Property, Plant and Equipment [Line Items]
Estimated useful life	7 years
Maximum [Member] | Brand Technology Development And Other Equipment [Member]
Property, Plant and Equipment [Line Items]
Estimated useful life	5 years