Stockholders' Equity and Stock-Based Compensation - Stock-Based Compensation Expense in Consolidated Statement of Operations (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 28, 2024	Sep. 30, 2023	Sep. 24, 2022
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	$ 82.3	$ 79.6	$ 66.7
Cost of revenues
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	10.7	10.5	9.1
Research and development
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	10.3	10.5	8.8
Selling and marketing
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	13.4	12.0	10.5
General and Administrative Expense
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	47.8	46.6	38.3
Restructuring Charges
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	$ 0.1	$ 0.0	$ 0.0