Selected Quarterly Financial Data (Schedule Of Selected Quarterly Financial Data) (Details) (USD $)	3 Months Ended																12 Months Ended
	Aug. 31, 2012		May 31, 2012		Feb. 29, 2012 store		Nov. 30, 2011		Aug. 31, 2011		May 31, 2011		Feb. 28, 2011		Nov. 30, 2010		Aug. 31, 2012	Aug. 31, 2011	Aug. 31, 2010
Selected Quarterly Financial Data [Abstract]
Total revenues	$ 150,940,000	[1]	$ 149,427,000	[1]	$ 115,084,000	[1]	$ 128,279,000	[1]	$ 151,184,000	[1]	$ 152,098,000	[1]	$ 113,523,000	[1]	$ 129,146,000	[1]	$ 543,730,000	$ 545,951,000	$ 550,926,000
Income from operations	30,902,000		30,736,000		10,548,000		16,754,000		27,248,000		28,667,000		9,601,000		17,792,000		88,940,000	83,308,000	70,881,000
Net income (loss)	14,502,000	[2]	14,407,000	[2]	1,677,000	[2]	5,499,000	[2]	12,286,000	[2]	(4,651,000)	[2]	4,348,000	[2]	7,242,000	[2]	36,085,000	19,225,000	21,209,000
Basic income (loss) per share	$ 0.25	[3]	$ 0.24	[3]	$ 0.03	[3]	$ 0.09	[3]	$ 0.20	[3]	$ (0.08)	[3]	$ 0.07	[3]	$ 0.12	[3]	$ 0.60	$ 0.31	$ 0.35
Diluted income (loss) per share	$ 0.25	[3]	$ 0.24	[3]	$ 0.03	[3]	$ 0.09	[3]	$ 0.20	[3]	$ (0.08)	[3]	$ 0.07	[3]	$ 0.12	[3]	$ 0.60	$ 0.31	$ 0.34
Number of refranchised company Drive-Ins					34
Gain (loss) from early extinguishment of debt											(28,200,000)		5,200,000					(23,035,000)	(314,000)
Income tax benefit relating to the favorable settlement of state tax matters															$ 1,100,000

[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.

[2] Includes a $5.2 million gain and a $28.2 million loss from early extinguishments of debt in the second and third quarters of fiscal year 2011, respectively, and a $1.1 million tax benefit recognized during the first quarter of fiscal year 2011 relating to the favorable settlement of state tax audits.

[3] The sum of per share data may not agree to annual amounts due to rounding.