Property, Equipment And Capital Leases (Narrative) (Details) $ in Thousands	12 Months Ended
	Aug. 31, 2017 USD ($) drive-in	Aug. 31, 2016 USD ($)	Aug. 31, 2015 USD ($)
Property, Plant and Equipment [Line Items]
Property and equipment, at cost	$ 570,686	$ 722,530
Accumulated depreciation related to buildings and equipment	272,233	345,284
Interest costs capitalized	600	600	$ 400
Property And Equipment [Member]
Property, Plant and Equipment [Line Items]
Depreciation expense	35,600	$ 40,400	$ 41,700
Leased To Franchisees And Other Parties [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, at cost	110,800
Accumulated depreciation related to buildings and equipment	$ 45,000
Drive-ins under construction
Property, Plant and Equipment [Line Items]
Drive-ins under construction | drive-in	0