Summary Of Significant Accounting Policies (Narrative) (Details) $ in Thousands	12 Months Ended
	Aug. 31, 2016 USD ($) segment	Aug. 31, 2015 USD ($)	Aug. 31, 2014 USD ($)	Nov. 30, 2015 USD ($)
Summary Of Significant Accounting Policies [Line Items]
Number of operating segments | segment	1
Number of reportable segments | segment	1
Total restricted cash	$ 16,000
Restricted cash (current)	15,873	$ 13,246
Restricted cash (noncurrent)	140	6,524
Goodwill impairment	0	0
Advertising and promotion costs	$ 23,400	24,500	$ 22,400
Reimbursed Sonic Brand Fund administration costs, percent	15.00%
Reimbursed Sonic Brand Fund administration costs	$ 5,200	5,000	$ 4,400
Reimbursed Brand Technology Fund administration costs, percent	15.00%
Reimbursed Brand Technology Fund administration costs	$ 2,500
Current deferred tax assets reclassified to noncurrent		$ 2,164
Accounting Standards Update 2015-17 [Member]
Summary Of Significant Accounting Policies [Line Items]
Current deferred tax assets reclassified to noncurrent				$ 2,200