Quarterly Financial Data (Unaudited) (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended									12 Months Ended
	Aug. 25, 2012	May 26, 2012		Feb. 25, 2012	Nov. 26, 2011	Aug. 27, 2011	May 28, 2011	Feb. 26, 2011	Nov. 27, 2010	Aug. 25, 2012	Aug. 27, 2011	Aug. 28, 2010
Quarterly Financial Data (Unaudited) [Abstract]
Revenues	$ 312,374	$ 320,931		$ 309,959	$ 313,025	$ 290,874	$ 291,567	$ 278,595	$ 273,090	$ 1,256,289	$ 1,134,126	$ 1,025,939
Income before income taxes	35,503	42,360	[1]	31,086	41,785	28,053	28,454	26,344	37,721	150,734	120,572	122,852
Provision for income taxes	12,971	14,901		11,890	15,983	10,039	10,023	10,067	13,957	55,745	44,086	46,444
Net income	22,532	27,459	[1]	19,196	25,802	18,014	18,431	16,277	23,764	94,989	76,486	76,408
Weighted average number of shares outstanding - basic
Common Stock (in shares)										19,916	19,854	19,564
Common Class A [Member]
Quarterly Financial Data (Unaudited) [Abstract]
Net income										74,643	59,944	59,921
Income per share - basic
Common Stock (in dollars per share)	$ 1.19	$ 1.45	[1]	$ 1.01	$ 1.37	$ 0.95	$ 0.98	$ 0.86	$ 1.26	$ 5.02	$ 4.05	$ 4.11
Income per share - diluted
Common Stock (in dollars per share)	$ 1.13	$ 1.37	[1]	$ 0.96	$ 1.30	$ 0.90	$ 0.93	$ 0.82	$ 1.20	$ 4.76	$ 3.85	$ 3.90
Income allocated to - basic
Common Stock	17,717	21,587	[1]	15,081	20,258	14,132	14,453	12,750	18,604	74,643	59,944	59,921
Income allocated to - diluted
Common Stock	22,153	26,993	[1]	18,863	25,350	17,698	18,105	15,983	23,330	93,358	75,118	75,827
Weighted average number of shares outstanding - basic
Common Stock (in shares)	14,912	14,905		14,873	14,838	14,822	14,810	14,778	14,753	14,882	14,791	14,570
Weighted average number of shares outstanding - diluted
Common Stock (in shares)	19,664	19,646		19,605	19,557	19,559	19,549	19,528	19,487	19,616	19,532	19,458
Common Class B [Member]
Quarterly Financial Data (Unaudited) [Abstract]
Net income										18,630	15,104	15,875
Income per share - basic
Common Stock (in dollars per share)	$ 0.95	$ 1.16	[1]	$ 0.81	$ 1.09	$ 0.76	$ 0.78	$ 0.69	$ 1.01	$ 4.01	$ 3.24	$ 3.29
Income allocated to - basic
Common Stock	$ 4,416	$ 5,381	[1]	$ 3,765	$ 5,068	$ 3,549	$ 3,635	$ 3,218	$ 4,704	$ 18,630	$ 15,104	$ 15,875
Weighted average number of shares outstanding - basic
Common Stock (in shares)	4,647	4,644		4,640	4,641	4,653	4,656	4,661	4,663	4,643	4,658	4,823

[1] In the third fiscal quarter of 2012, operating results benefited from a settlement of environmental litigation that resulted in the Company recording a $6.7 million pre-tax gain. This gain translated into a $0.21 benefit to the Company's diluted earnings per share.