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. 26, 2017	May 27, 2017	Feb. 25, 2017	Nov. 26, 2016	Aug. 27, 2016	May 28, 2016	Feb. 27, 2016	Nov. 28, 2015	Aug. 26, 2017	Aug. 27, 2016	Aug. 29, 2015
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Net income available to shareholders	$ (4,896)	$ 24,362	$ 22,516	$ 28,214	$ 35,494	$ 30,144	$ 23,498	$ 35,890	$ 70,196	$ 125,026	$ 124,299
Allocation of net income for Basic:
Common Stock									$ 70,196	$ 125,026	$ 124,299
Weighted average number of shares for Basic:
Common Stock (in shares)									20,284	20,168	20,098
Common Stock
Allocation of net income for Basic:
Common Stock	$ (3,908)	$ 19,307	$ 17,836	$ 22,342	$ 28,097	$ 23,939	$ 18,691	$ 28,539	$ 55,903	$ 99,282	$ 98,665
Weighted average number of shares for Basic:
Common Stock (in shares)	15,402	15,326	15,305	15,285	15,268	15,253	15,241	15,218	15,382	15,245	15,182
Earnings per share for Basic:
Common Stock (in dollars per share)	$ (0.25)	$ 1.26	$ 1.17	$ 1.46	$ 1.84	$ 1.57	$ 1.23	$ 1.88	$ 3.63	$ 6.51	$ 6.50
Class B Common Stock
Allocation of net income for Basic:
Common Stock	$ (978)	$ 4,883	$ 4,518	$ 5,668	$ 7,139	$ 6,061	$ 4,704	$ 7,193	$ 13,915	$ 25,093	$ 24,761
Weighted average number of shares for Basic:
Common Stock (in shares)	4,818	4,846	4,846	4,847	4,850	4,827	4,795	4,795	4,786	4,816	4,763
Earnings per share for Basic:
Common Stock (in dollars per share)	$ (0.20)	$ 1.01	$ 0.93	$ 1.17	$ 1.47	$ 1.26	$ 0.98	$ 1.50	$ 2.91	$ 5.21	$ 5.20
Unvested participating shares
Allocation of net income for Basic:
Common Stock									$ 378	$ 651	$ 873
Weighted average number of shares for Basic:
Common Stock (in shares)									116	107	153