Property, Equipment And Capital Leases (Narrative) (Details) $ in Thousands	12 Months Ended
	Aug. 31, 2016 USD ($) item	Aug. 31, 2015 USD ($)	Aug. 31, 2014 USD ($)
Property, Plant and Equipment [Line Items]
Property and equipment, at cost	$ 739,418	$ 733,778
Accumulated depreciation related to buildings and equipment	352,390	330,219
Interest costs capitalized	600	400	$ 500
Property And Equipment [Member]
Property, Plant and Equipment [Line Items]
Depreciation expense	40,400	$ 41,700	$ 37,600
Leased To Franchisees And Other Parties [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, at cost	156,600
Accumulated depreciation related to buildings and equipment	$ 62,500
Drive-ins under construction
Property, Plant and Equipment [Line Items]
Drive-ins under construction | item	11