Refranchising of Company Drive-Ins (Details) - franchise	12 Months Ended
	Aug. 31, 2017	Aug. 31, 2016	Jun. 30, 2016
Franchisor Disclosure [Line Items]
Franchise restaurant ownership target			95.00%
Number of refranchised Company Drive-Ins		38
Refranchising Initiative 2016 [Member]
Franchisor Disclosure [Line Items]
Number of refranchised Company Drive-Ins		29
Refranchising Initiative 2016 [Member] | Non-controlling operating interest [Member]
Franchisor Disclosure [Line Items]
Number of refranchised Company Drive-Ins		25
Refranchising Initiative 2017 [Member]
Franchisor Disclosure [Line Items]
Number of refranchised Company Drive-Ins	110
Refranchising Initiative 2017 [Member] | Non-controlling operating interest [Member]
Franchisor Disclosure [Line Items]
Number of refranchised Company Drive-Ins	106