Note 7 - Net Income Per Share (Details) - Summary of Earnings Per Share Basic Two Class Method (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Feb. 28, 2015	Mar. 01, 2014	Feb. 28, 2015	Mar. 01, 2014
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Net income	$ 25,446	$ 25,647	$ 62,859	$ 60,109
Allocation of net income for Basic	25,446	25,647	62,859	60,109
Weighted average number of shares for Basic (in Shares)	20,118	20,052	20,089	20,031
Common Class A [Member]
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Allocation of net income for Basic	20,182	20,267	49,834	47,479
Weighted average number of shares for Basic (in Shares)	15,185	15,077	15,156	15,053
Earnings per share for Basic (in Dollars per share)	$ 1.33	$ 1.34	$ 3.29	$ 3.15
Common Class B [Member]
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Allocation of net income for Basic	5,041	5,041	12,472	11,836
Weighted average number of shares for Basic (in Shares)	4,741	4,687	4,741	4,690
Earnings per share for Basic (in Dollars per share)	$ 1.06	$ 1.08	$ 2.63	$ 2.52
Unvested Participating Shares [Member]
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Allocation of net income for Basic	$ 223	$ 339	$ 553	$ 794
Weighted average number of shares for Basic (in Shares)	192	288	192	288