Segment Information (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended																12 Months Ended
	Aug. 31, 2013		May 31, 2013		Feb. 28, 2013		Nov. 30, 2012		Aug. 31, 2012		May 31, 2012		Feb. 29, 2012		Nov. 30, 2011		Aug. 31, 2013 segment	Aug. 31, 2012	Aug. 31, 2011
Segment Information [Abstract]
Reportable business segments																	2
Company Drive-Ins																	$ 402,296	$ 404,443	$ 410,820
Franchise Operations																	135,522	134,588	131,894
Unallocated revenues																	4,767	4,699	3,237
Total revenues	158,802	[1]	146,634	[1]	111,141	[1]	126,008	[1]	150,940	[1]	149,427	[1]	115,084	[1]	128,279	[1]	542,585	543,730	545,951
Company Drive-Ins																	59,087	56,973	54,584
Franchise Operations																	135,522	134,588	131,894
Unallocated income																	2,824	5,230	3,822
Selling, general and administrative																	(66,022)	(65,173)	(64,943)
Depreciation and amortization																	(40,387)	(41,914)	(41,225)
Provision for impairment of long-lived assets																	(1,776)	(764)	(824)
Income from operations	30,033		29,994		12,018		17,203		30,902		30,736		10,548		16,754		89,248	88,940	83,308
Net interest expense																	(32,949)	(30,978)	(54,929)
Income before income taxes																	$ 56,299	$ 57,962	$ 28,379

[1] Revenues were impacted by the refranchising of 34 Company Drive-Ins during the latter part of the Company’s second fiscal quarter of 2012.