Marketable Securities (Details) - USD ($) $ in Millions	3 Months Ended
	Dec. 27, 2024	Sep. 27, 2024
Debt Securities, Available-for-sale [Line Items]
Marketable securities, noncurrent, maximum contractual maturity	2 years
Current assets
Debt Securities, Available-for-sale [Line Items]
Marketable securities, current	$ 136.7	$ 194.1
Noncurrent assets
Debt Securities, Available-for-sale [Line Items]
Marketable securities, noncurrent	15.6	11.4
U.S. Treasury and government securities | Current assets
Debt Securities, Available-for-sale [Line Items]
Marketable securities, current	45.4	39.0
U.S. Treasury and government securities | Noncurrent assets
Debt Securities, Available-for-sale [Line Items]
Marketable securities, noncurrent	15.5	11.1
Corporate bonds and notes | Current assets
Debt Securities, Available-for-sale [Line Items]
Marketable securities, current	91.3	155.0
Corporate bonds and notes | Noncurrent assets
Debt Securities, Available-for-sale [Line Items]
Marketable securities, noncurrent	0.1	0.3
Municipal bonds | Current assets
Debt Securities, Available-for-sale [Line Items]
Marketable securities, current	0.0	0.1
Municipal bonds | Noncurrent assets
Debt Securities, Available-for-sale [Line Items]
Marketable securities, noncurrent	$ 0.0	$ 0.0