Property, Equipment And Capital Leases (Narrative) (Details) $ in Thousands	12 Months Ended
	Aug. 31, 2015 USD ($) item	Aug. 31, 2014 USD ($)	Aug. 31, 2013 USD ($)
Property, Plant and Equipment [Line Items]
Property and equipment, at cost	$ 733,778	$ 720,776
Accumulated depreciation related to buildings and equipment	330,219	298,580
Interest costs capitalized	400	500	$ 700
Property And Equipment [Member]
Property, Plant and Equipment [Line Items]
Depreciation expense	41,700	$ 37,600	$ 35,600
Leased To Franchisees And Other Parties [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, at cost	165,800
Accumulated depreciation related to buildings and equipment	$ 63,100
Drive-ins under construction
Property, Plant and Equipment [Line Items]
Drive-ins under construction | item	3