Summary of Significant Accounting Policies - Computation of Basic Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended								12 Months Ended
	Aug. 25, 2018	May 26, 2018	Feb. 24, 2018	Nov. 25, 2017	Aug. 26, 2017	May 27, 2017	Feb. 25, 2017	Nov. 26, 2016	Aug. 25, 2018	Aug. 26, 2017	Aug. 27, 2016
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Net income available to shareholders	$ 34,952	$ 36,359	$ 58,378	$ 34,206	$ (4,896)	$ 24,362	$ 22,516	$ 28,214	$ 163,895	$ 70,196	$ 125,026
Allocation of net income for Basic:
Common Stock									$ 163,895	$ 70,196	$ 125,026
Weighted average number of shares for Basic:
Common Stock (in shares)									19,811	20,284	20,168
Common Stock
Allocation of net income for Basic:
Common Stock	$ 29,312	$ 30,034	$ 46,744	$ 27,384	$ (3,908)	$ 19,307	$ 17,836	$ 22,342	$ 133,802	$ 55,903	$ 99,282
Weighted average number of shares for Basic:
Common Stock (in shares)	15,429	15,446	15,481	15,462	15,402	15,326	15,305	15,285	15,454	15,382	15,245
Income per share for Basic:
Common Stock (in dollars per share)	$ 1.90	$ 1.94	$ 3.02	$ 1.77	$ (0.25)	$ 1.26	$ 1.17	$ 1.46	$ 8.66	$ 3.63	$ 6.51
Class B Common Stock
Allocation of net income for Basic:
Common Stock	$ 5,640	$ 6,325	$ 11,634	$ 6,822	$ (978)	$ 4,883	$ 4,518	$ 5,668	$ 30,093	$ 13,915	$ 25,093
Weighted average number of shares for Basic:
Common Stock (in shares)	3,711	4,087	4,816	4,816	4,818	4,846	4,846	4,847	4,357	4,786	4,816
Income per share for Basic:
Common Stock (in dollars per share)	$ 1.52	$ 1.55	$ 2.42	$ 1.42	$ (0.20)	$ 1.01	$ 0.93	$ 1.17	$ 6.91	$ 2.91	$ 5.21
Unvested participating shares
Allocation of net income for Basic:
Common Stock									$ 0	$ 378	$ 651
Weighted average number of shares for Basic:
Common Stock (in shares)									0	116	107