v3.25.1
Fair Value Measurements - Cash and Cash Equivalents (Details) - USD ($)
$ in Millions
6 Months Ended
Mar. 29, 2025
Sep. 28, 2024
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Cost $ 1,429.5 $ 2,160.2
Short-Term Investments, Unrealized Gain 0.3  
Short-Term Investments, Unrealized Loss 0.0  
Total available-for-sale securities 371.8 992.9
Cash, Cash Equivalents, and Short-Term Investments 1,620.7  
Cash, Cash Equivalents, and Short-Term Investments, Fair Value 1,621.0  
Investments 191.5  
Cash    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Cost 1,249.2  
Unrealized Gains 0.0  
Unrealized Losses 0.0  
Fair Value 1,249.2  
Money Market Funds    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Cost 180.3  
Unrealized Gains 0.0  
Unrealized Losses 0.0  
Fair Value 180.3 341.7
Investments 0.0  
US Treasury Securities    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Cost 0.0  
Debt Securities, Available-for-Sale, Amortized Cost, Excluding Accrued Interest, after Allowance for Credit Loss 191.2  
Investments, Unrealized Gain 0.3  
Investments, Unrealized Loss 0.0  
Total available-for-sale securities 191.5 $ 626.3
Investments $ 191.5