Shareholders' Equity (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands		3 Months Ended		6 Months Ended
	Mar. 31, 2020	Feb. 29, 2020	Mar. 02, 2019	Feb. 29, 2020	Mar. 02, 2019
Components Of Shareholders Equity [Line Items]
Treasury stock reissued to fund plan, shares		19	20	35	33
Cash dividends paid per common share					$ 1.26
Cash dividends paid				$ 360,815	$ 69,551
Subsequent Event [Member]
Components Of Shareholders Equity [Line Items]
Dividends payable per share	$ 0.75
Dividend payable date	Apr. 28, 2020
Dividends record date	Apr. 14, 2020
Dividend payable amount	$ 41,668
Regular Dividends [Member]
Components Of Shareholders Equity [Line Items]
Cash dividends paid per common share				$ 1.50
Cash dividends paid				$ 83,181
Special Dividends [Member]
Components Of Shareholders Equity [Line Items]
Cash dividends paid per common share				$ 5.00
Cash dividends paid				$ 277,634
Class A Common Stock [Member]
Components Of Shareholders Equity [Line Items]
Common stock shares repurchased		3	275	44	315
Treasury stock repurchased, and treasury stock repurchased and retired, shares			275		1,053
Treasury stock repurchased, and treasury stock repurchased and retired, amount			$ 20,898		$ 84,425
Number of shares authorized for repurchase		1,157		1,157
Treasury Stock [Member] | Class A Common Stock [Member]
Components Of Shareholders Equity [Line Items]
Purchase of treasury stock		$ 199	$ 20,898	$ 3,208	$ 24,098