Quarterly Financial Data (Unaudited) (Details) - USD ($) $ / shares in Units, shares in Thousands	3 Months Ended									12 Months Ended
	Aug. 27, 2016	[1]	May 28, 2016	Feb. 27, 2016	Nov. 28, 2015	Aug. 29, 2015	May 30, 2015	Feb. 28, 2015	Nov. 29, 2014	Aug. 27, 2016	Aug. 29, 2015	Aug. 30, 2014
Common Class A [Member]
Income per share – Basic (in dollars per share)	$ 1.84		$ 1.57	$ 1.23	$ 1.88	$ 1.51	$ 1.70	$ 1.33	$ 1.96	$ 6.51	$ 6.50	$ 6.29
Income per share – Diluted (in dollars per share)	$ 1.74		$ 1.49	$ 1.16	$ 1.78	$ 1.43	$ 1.61	$ 1.26	$ 1.85	$ 6.17	$ 6.15	$ 5.95
Income allocated to – Basic	$ 28,097,000		$ 23,939,000	$ 18,691,000	$ 28,539,000	$ 23,011,000	$ 25,817,000	$ 20,182,000	$ 29,649,000	$ 99,282,000	$ 98,665,000	$ 94,849,000
Income allocated to – Diluted	$ 35,250,000		$ 30,007,000	$ 23,401,000	$ 35,741,000	$ 28,821,000	$ 32,310,000	$ 25,235,000	$ 37,101,000	$ 124,409,000	$ 123,472,000	$ 118,626,000
Weighted average number of shares outstanding – Basic (in shares)	15,268		15,253	15,241	15,218	15,210	15,207	15,185	15,128	15,245	15,182	15,080
Weighted average number of shares outstanding – Diluted (in shares)	20,223		20,183	20,138	20,132	20,142	20,118	20,065	20,008	20,154	20,079	19,939
Common Class B [Member]
Income per share – Basic (in dollars per share)	$ 1.47		$ 1.26	$ 0.98	$ 1.50	$ 1.21	$ 1.36	$ 1.06	$ 1.57	$ 5.21	$ 5.20	$ 5.03
Income allocated to – Basic	$ 7,139,000		$ 6,061,000	$ 4,704,000	$ 7,193,000	$ 5,803,000	$ 6,483,000	$ 5,041,000	$ 7,434,000	$ 25,093,000	$ 24,761,000	$ 23,705,000
Weighted average number of shares outstanding – Basic (in shares)	4,850		4,827	4,795	4,795	4,795	4,773	4,741	4,741	4,816	4,763	4,711
Revenues	$ 363,766,000		$ 367,799,000	$ 363,097,000	$ 373,384,000	$ 359,208,000	$ 365,574,000	$ 361,462,000	$ 370,361,000	$ 1,468,046,000	$ 1,456,605,000	$ 1,394,897,000
Income before income taxes	57,315,000		48,699,000	38,999,000	58,358,000	46,215,000	52,843,000	41,376,000	60,834,000	203,371,000	201,268,000	195,351,000
Provision for income taxes	21,821,000		18,555,000	15,501,000	22,468,000	17,274,000	20,344,000	15,930,000	23,421,000	78,345,000	76,969,000	75,426,000
Net income	$ 35,494,000		$ 30,144,000	$ 23,498,000	$ 35,890,000	$ 28,941,000	$ 32,499,000	$ 25,446,000	$ 37,413,000	$ 125,026,000	$ 124,299,000	$ 119,925,000
Income per share – Diluted (in dollars per share)										$ 6.17	$ 6.15	$ 5.95
Income allocated to – Diluted										$ 124,409,000	$ 123,472,000	$ 118,626,000
Weighted average number of shares outstanding – Diluted (in shares)										20,154	20,079	19,939

[1] In the fourth fiscal quarter of 2016, operating results benefited from a settlement of environmental litigation that resulted in the Company recording a $15.9 million pre-tax gain. This gain translated into a $0.48 benefit to the Company's diluted earnings per share.