Leases (Narrative) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Aug. 31, 2012 item
Leases [Line Items]
Lease expiration date	Sep. 30, 2030
Direct financing leases, expiration period	9 years
Lease renewal option, minimum	1
Lease renewal option, maximum	4
Lease renewal options, initial term period	5 years
Minimum operating rentals receivable under noncancelable subleases	$ 35.3
Minimum capital rentals receivable under noncancelable subleases	$ 2.1
Company Drive Ins [Member]
Leases [Line Items]
Lease expiration date	Aug. 31, 2030
Refranchised Drive Ins [Member]
Leases [Line Items]
Lease renewal options, initial term period	5 years
Term of operating leases	15 years
Number of lease agreements executed	2
Lease renewal options	4