Refranchising Initiative Summary of the pretax activity recorded as a result of the refranchising initiative (Details) $ in Thousands	3 Months Ended		6 Months Ended
	Feb. 28, 2017 USD ($) franchise	Nov. 30, 2016 franchise	Feb. 28, 2018 USD ($)	Feb. 28, 2017 USD ($) franchise
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Proceeds from sales of Company Drive-Ins			$ 4,990	$ 27,073
Refranchising Initiative 2017 [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of refranchised Company Drive-Ins | franchise	54			110
Proceeds from sales of Company Drive-Ins	$ 11,086			$ 20,036
Assets sold, net of retained minority investment	(3,277)			(8,738)
Initial and subsequent lease payments for real estate option	414			(3,396)
Goodwill related to sales of Company Drive-Ins	(589)			(966)
Deferred gain for real estate option	(1,040)			(1,040)
Gain (loss) on assets held for sale	194			(65)
Refranchising initiative gains, net	$ 6,788			$ 5,831
Refranchised company drive-ins with direct financing lease | franchise		53