Note 7 - Net Income Per Share (Details) - Summary of Earnings Per Share Diluted 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, Diluted, by Common Class, Including Two Class Method [Line Items]
As reported - Basic	$ 25,446	$ 25,647	$ 62,859	$ 60,109
Add: Undistributed earnings allocated to unvested participating shares	217	329	540	776
Less: Undistributed earnings reallocated to unvested participating shares	(205)	(311)	(511)	(734)
Diluted EPS – Common Stock	25,235	25,326	62,335	59,357
Diluted EPS – Common Stock (in Shares)	20,065	19,924	20,028	19,897
Diluted EPS – Common Stock (in Dollars per share)	$ 1.26	$ 1.27	$ 3.11	$ 2.98
Common Class A [Member]
Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items]
As reported - Basic	20,182	20,267	49,834	47,479
As reported - Basic (in Shares)	15,185	15,077	15,156	15,053
As reported - Basic (in Dollars per share)	$ 1.33	$ 1.34	$ 3.29	$ 3.15
Dilutive potential common shares (in Shares)	139	160	131	154
Diluted EPS – Common Stock	25,235	25,326	62,335	59,357
Diluted EPS – Common Stock (in Shares)	20,065	19,924	20,028	19,897
Diluted EPS – Common Stock (in Dollars per share)	$ 1.26	$ 1.27	$ 3.11	$ 2.98
Common Class B [Member]
Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items]
As reported - Basic	5,041	5,041	12,472	11,836
As reported - Basic (in Shares)	4,741	4,687	4,741	4,690
As reported - Basic (in Dollars per share)	$ 1.06	$ 1.08	$ 2.63	$ 2.52
Dilutive potential common shares	$ 5,041	$ 5,041	$ 12,472	$ 11,836
Dilutive potential common shares (in Shares)	4,741	4,687	4,741	4,690