Note 7 - Net Income Per Share - Summary of Earnings Per Share, Diluted, Two Class Method (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Feb. 25, 2017	Feb. 27, 2016	Feb. 25, 2017	Feb. 27, 2016
Allocation of net income for Basic	$ 22,516	$ 23,498	$ 50,730	$ 59,388
Add: Undistributed earnings allocated to unvested participating shares	158	100	357	253
Less: Undistributed earnings reallocated to unvested participating shares	(150)	(94)	(338)	(240)
Diluted EPS – Common Stock	$ 22,362	$ 23,401	$ 50,381	$ 59,141
Diluted EPS – Common Stock (in shares)	20,263	20,138	20,250	20,127
Diluted EPS – Common Stock (in dollars per share)	$ 1.10	$ 1.16	$ 2.49	$ 2.94
Common Class A [Member]
Allocation of net income for Basic	$ 17,836	$ 18,691	$ 40,178	$ 47,232
As reported - Basic (in shares)	15,305	15,241	15,295	15,230
Earnings per share for Basic (in dollars per share)	$ 1.17	$ 1.23	$ 2.63	$ 3.10
Dilutive potential common shares (in shares)	112	102	109	102
Diluted EPS – Common Stock	$ 22,362	$ 23,401	$ 50,381	$ 59,141
Diluted EPS – Common Stock (in shares)	20,263	20,138	20,250	20,127
Diluted EPS – Common Stock (in dollars per share)	$ 1.10	$ 1.16	$ 2.49	$ 2.94
Common Class B [Member]
Allocation of net income for Basic	$ 4,518	$ 4,704	$ 10,184	$ 11,896
As reported - Basic (in shares)	4,846	4,795	4,846	4,795
Earnings per share for Basic (in dollars per share)	$ 0.93	$ 0.98	$ 2.10	$ 2.48