Quarterly Financial Data (Unaudited) (Details) (USD $) In Thousands, except Per Share data	3 Months Ended								12 Months Ended
	Aug. 27, 2011	May 28, 2011	Feb. 26, 2011	Nov. 27, 2010	Aug. 28, 2010	May 29, 2010	Feb. 27, 2010	Nov. 28, 2009	Aug. 27, 2011	Aug. 28, 2010	Aug. 29, 2009
Quarterly Financial Data (Unaudited) [Abstract]
Revenues	$ 290,874	$ 291,567	$ 278,595	$ 273,090	$ 254,950	$ 261,248	$ 253,562	$ 256,179	$ 1,134,126	$ 1,025,939	$ 1,013,416
Income before income taxes	28,053	28,454	26,344	37,721	27,503	29,723	26,658	38,968	120,572	122,852	126,465
Provision for income taxes	10,039	10,023	10,067	13,957	10,211	10,409	10,432	15,392	44,086	46,444	50,613
Net income	18,014	18,431	16,277	23,764	17,292	19,314	16,226	23,576	76,486	76,408	75,852
Income per share - basic
Common Stock (in dollars per share)									$ 4.05	$ 4.11	$ 4.14
Income per share - diluted
Common Stock (in dollars per share)									$ 3.85	$ 3.90	$ 3.92
Income allocated to - diluted
Common Stock									75,118	75,827	75,852
Weighted average number of shares outstanding - basic
Common Stock (in shares)									19,854	19,564	19,329
Weighted average number of shares outstanding - diluted
Common Stock (in shares)									19,532	19,458	19,373
Common Class A [Member]
Income per share - basic
Common Stock (in dollars per share)	$ 0.95	$ 0.98	$ 0.86	$ 1.26	$ 0.92	$ 1.03	$ 0.88	$ 1.28	$ 4.05	$ 4.11	$ 4.14
Income per share - diluted
Common Stock (in dollars per share)	$ 0.90	$ 0.93	$ 0.82	$ 1.20	$ 0.87	$ 0.98	$ 0.83	$ 1.21	$ 3.85	$ 3.90	$ 3.92
Income allocated to - basic
Common Stock	14,132	14,453	12,750	18,604	13,536	15,145	12,750	18,516	59,944	59,921	59,526
Income allocated to - diluted
Common Stock	17,698	18,105	15,983	23,330	16,976	19,106	16,226	23,576	75,118	75,827	75,852
Weighted average number of shares outstanding - basic
Common Stock (in shares)	14,822	14,810	14,778	14,753	14,751	14,645	14,467	14,440	14,791	14,570	14,394
Weighted average number of shares outstanding - diluted
Common Stock (in shares)	19,559	19,549	19,528	19,487	19,472	19,490	19,477	19,434	19,532	19,458	19,373
Common Class B [Member]
Quarterly Financial Data (Unaudited) [Abstract]
Net income									15,104	15,875	16,326
Income per share - basic
Common Stock (in dollars per share)	$ 0.76	$ 0.78	$ 0.69	$ 1.01	$ 0.73	$ 0.83	$ 0.71	$ 1.03	$ 3.24	$ 3.29	$ 3.31
Income allocated to - basic
Common Stock	$ 3,549	$ 3,635	$ 3,218	$ 4,704	$ 3,424	$ 3,949	$ 3,476	$ 5,060	$ 15,104	$ 15,875	$ 16,326
Weighted average number of shares outstanding - basic
Common Stock (in shares)	4,653	4,656	4,661	4,663	4,663	4,766	4,931	4,932	4,658	4,823	4,935
Weighted average number of shares outstanding - diluted
Common Stock (in shares)									4,658	4,823	4,935