Schedule II - Valuation And Qualifying Accounts (Details) - USD ($) $ in Thousands	12 Months Ended
	Aug. 31, 2017	Aug. 31, 2016	Aug. 31, 2015
Allowance For Doubtful Accounts And Notes Receivable [Member]
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Year	$ 1,041	$ 1,105	$ 1,771
Additions Charged to Costs and Expenses	113	(53)	(81)
Amounts Written Off Against the Allowance	(23)	(13)	(601)
(Transfer) Recoveries	0	2	16
Balance at End of Year	1,131	1,041	1,105
Accrued Liability For Drive-In Closings And Disposals [Member]
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Year	611	807	871
Additions Charged to Costs and Expenses	178	208	367
Amounts Written Off Against the Allowance	(243)	(376)	(422)
(Transfer) Recoveries	(14)	(28)	(9)
Balance at End of Year	$ 532	$ 611	$ 807