Shareholders' Equity (Details) - USD ($) $ / shares in Units, $ in Thousands			1 Months Ended	12 Months Ended
	Oct. 24, 2017	Aug. 19, 2016	Aug. 31, 2016	Sep. 02, 2017	Sep. 03, 2016	Aug. 29, 2015	Jul. 31, 2016
Components Of Shareholders Equity [Line Items]
Common stock shares repurchased			4,973,000
Share Price			$ 72.50
Purchase of treasury stock			$ 360,566	$ 48,869	$ 384,111	$ 33,414
Preferred stock, shares authorized				5,000,000	5,000,000
Preferred stock, shares issued				0	0
Preferred stock, shares outstanding				0	0
Subsequent Event [Member]
Components Of Shareholders Equity [Line Items]
Dividends declared date	Oct. 24, 2017
Dividends payable per share	$ 0.48
Dividend payable date	Nov. 28, 2017
Dividends record date	Nov. 14, 2017
Dividend payable amount	$ 27,068,000
Class A Common Stock [Member]
Components Of Shareholders Equity [Line Items]
Stock repurchase, fees and expenses				$ 1,587
Cost of repurchase, per share				$ 72.82
Retirement of treasury stock, Shares				4,973,000
Class A common stock shares repurchase amount, per share				$ 72.82
Class A Common Stock [Member] | Tender Offer [Member]
Components Of Shareholders Equity [Line Items]
Common stock shares repurchased			3,821,000
Share Price			$ 72.50
Authorized amount of repurchase							$ 300
Class A Common Stock [Member] | Tender Offer [Member] | Minimum [Member]
Components Of Shareholders Equity [Line Items]
Share Price							$ 66.00
Class A Common Stock [Member] | Tender Offer [Member] | Maximum [Member]
Components Of Shareholders Equity [Line Items]
Share Price							$ 72.50
Class A Common Stock [Member] | Purchases From Class B Holders [Member]
Components Of Shareholders Equity [Line Items]
Common stock shares repurchased		1,152,000
Share Price		$ 72.50
Class A Treasury Stock [Member]
Components Of Shareholders Equity [Line Items]
Common stock shares repurchased				685,000	5,344,000	444,000
Purchase of treasury stock				$ 48,869	$ 384,111	$ 33,414
Cost of share repurchase					$ (362,153)
Retirement of treasury stock, Shares					4,973,000
Shares repurchased by the company for associates' tax withholding liability associated with share-based compensation				43,000	72,000
Maximum number of shares that can be repurchased				802,000
Number of shares authorized for repurchase				5,000,000
Treasury stock reissued to fund plan. shares				57,000	64,000