Net Income Per Share, Schedule of Earnings Per Share, Basic, Two Class Method (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Feb. 25, 2012	Feb. 26, 2011	Feb. 25, 2012	Feb. 26, 2011
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Net income	$ 19,196	$ 16,277	$ 44,998	$ 40,041
Weighted average number of shares - basic	19,907	19,847	19,892	19,838
Common Class A [Member]
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Net income	15,081	12,750	35,341	31,356
Weighted average number of shares - basic	14,873	14,778	14,856	14,766
Earning per share - basic (in amounts per share)	$ 1.01	$ 0.86	$ 2.38	$ 2.12
Common Class B [Member]
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Net income	3,765	3,218	8,832	7,921
Weighted average number of shares - basic	4,640	4,661	4,640	4,662
Earning per share - basic (in amounts per share)	$ 0.81	$ 0.69	$ 1.90	$ 1.70
Unvested Participating Shares [Member]
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Net income	$ 350	$ 309	$ 825	$ 764
Weighted average number of shares - basic	394	408	396	410