EMPLOYEE STOCK PLANS - Net Share-Based Compensation Expense (Details) - USD ($) $ in Millions	3 Months Ended
	Jan. 01, 2021	Jan. 03, 2020
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total share-based compensation expense	$ 16.7	$ 14.9
Income tax benefit for share-based compensation	(3.3)	(2.9)
Cost of revenues - Product
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total share-based compensation expense	1.0	0.8
Cost of revenues - Service
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total share-based compensation expense	1.6	1.3
Research and development
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total share-based compensation expense	1.9	1.2
Selling, general and administrative
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total share-based compensation expense	$ 12.2	$ 11.6