Refranchising of Company Drive-Ins (Details) $ in Thousands	12 Months Ended
	Aug. 31, 2018 USD ($) franchise	Aug. 31, 2017 USD ($) franchise	Aug. 31, 2016 USD ($) franchise	Jun. 30, 2016
Franchisor Disclosure [Line Items]
Number of refranchised Company Drive-Ins	8	5	9
Franchise restaurant, ownership percentage	95.00%			95.00%
Refranchising Initiative 2016 [Member]
Franchisor Disclosure [Line Items]
Refranchising initiative gains | $			$ 972
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]
Refranchising initiative gains | $		$ 6,758
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
2018 Refranchising [Member]
Franchisor Disclosure [Line Items]
Refranchising initiative gains | $	$ 3,200
2018 Refranchising [Member] | Non-controlling operating interest [Member]
Franchisor Disclosure [Line Items]
Number of refranchised Company Drive-Ins	41