Stockholders' Equity And Stock-Based Compensation Stockholders' Equity And Stock- Based Compensation - Dividends Declared (Details) - USD ($) $ / shares in Units, $ in Millions										12 Months Ended
		Dec. 08, 2021	Nov. 16, 2021	Aug. 19, 2021	Jul. 29, 2021	May 25, 2021	May 04, 2021	Feb. 19, 2021	Jan. 28, 2021	Sep. 24, 2021	Sep. 25, 2020	Sep. 27, 2019
Dividends Payable [Line Items]
Cash dividend declared per common share					$ 0.22		$ 0.22		$ 0.22	$ 0.91	$ 0.88	$ 0.79
Dividends				$ 22.3		$ 22.3		$ 22.4
Subsequent Event [Member]
Dividends Payable [Line Items]
Cash dividend declared per common share	[1]		$ 0.25
Dividends	[1]	$ 25.3

[1] The dividend payment amount is estimated based on the number of shares of our Class A and Class B common stock that we estimate will be outstanding as of the Record Date.