Note 7 - Net Income Per Share - Summary of Earnings Per Share, Basic, Two Class Method (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Nov. 26, 2016	Nov. 28, 2015
Net income available to shareholders	$ 28,214	$ 35,890
Income allocated to – Basic:
Allocation of net income for Basic	$ 28,214	$ 35,890
Weighted average number of shares outstanding – Basic:
Weighted average number of shares for Basic (in shares)	20,272	20,108
Common Class A [Member]
Income allocated to – Basic:
Allocation of net income for Basic	$ 22,342	$ 28,539
Weighted average number of shares outstanding – Basic:
Weighted average number of shares for Basic (in shares)	15,285	15,218
Income per share – Basic:
Earnings per share for Basic (in dollars per share)	$ 1.46	$ 1.88
Common Class B [Member]
Income allocated to – Basic:
Allocation of net income for Basic	$ 5,668	$ 7,193
Weighted average number of shares outstanding – Basic:
Weighted average number of shares for Basic (in shares)	4,847	4,795
Income per share – Basic:
Earnings per share for Basic (in dollars per share)	$ 1.17	$ 1.50
Unvested Participating Shares [Member]
Income allocated to – Basic:
Allocation of net income for Basic	$ 204	$ 158
Weighted average number of shares outstanding – Basic:
Weighted average number of shares for Basic (in shares)	140	95