Segment Information (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended																12 Months Ended
	Aug. 31, 2012		May 31, 2012		Feb. 29, 2012		Nov. 30, 2011		Aug. 31, 2011		May 31, 2011		Feb. 28, 2011		Nov. 30, 2010		Aug. 31, 2012 segment	Aug. 31, 2011	Aug. 31, 2010
Segment Information [Abstract]
Reportable business segments																	2
Company Drive-Ins																	$ 404,443	$ 410,820	$ 414,369
Franchise Operations																	134,588	131,894	132,016
Unallocated revenues																	4,699	3,237	4,541
Total revenues	150,940	[1]	149,427	[1]	115,084	[1]	128,279	[1]	151,184	[1]	152,098	[1]	113,523	[1]	129,146	[1]	543,730	545,951	550,926
Company Drive-Ins																	56,973	54,584	59,710
Franchise Operations																	134,588	131,894	132,016
Unallocated income																	5,230	3,822	3,778
Selling, general and administrative																	(65,173)	(64,943)	(66,847)
Depreciation and amortization																	(41,914)	(41,225)	(42,615)
Provision for impairment of long-lived assets																	(764)	(824)	(15,161)
Income from operations	30,902		30,736		10,548		16,754		27,248		28,667		9,601		17,792		88,940	83,308	70,881
Net interest expense																	30,978	54,929	36,073
Income before income taxes																	$ 57,962	$ 28,379	$ 34,808

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