Property, Equipment And Capital Leases (Narrative) (Details) $ in Thousands	12 Months Ended
	Aug. 31, 2018 USD ($) drive-in	Aug. 31, 2017 USD ($)	Aug. 31, 2016 USD ($)
Property, Plant and Equipment [Line Items]
Property and equipment, at cost	$ 559,485	$ 570,686
Accumulated depreciation related to buildings and equipment	271,940	272,233
Interest costs capitalized	400	600	$ 600
Property And Equipment [Member]
Property, Plant and Equipment [Line Items]
Depreciation expense	35,300	35,600	$ 40,400
Leased To Franchisees And Other Parties [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, at cost	155,500	110,800
Accumulated depreciation related to buildings and equipment	$ 63,200	$ 45,000
Drive-ins under construction
Property, Plant and Equipment [Line Items]
Drive-ins under construction | drive-in	2