EMPLOYEE STOCK PLANS - Share-based Compensation Expense (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Apr. 03, 2020	Mar. 29, 2019	Apr. 03, 2020	Mar. 29, 2019
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Allocated share-based compensation expense	$ 3.3	$ 3.0	$ 6.5	$ 5.6
Cost of revenues
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Allocated share-based compensation expense	0.3	0.4	0.6	0.7
Research and development
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Allocated share-based compensation expense	0.6	0.9	1.2	1.4
Selling, general and administrative
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Allocated share-based compensation expense	$ 2.4	$ 1.7	$ 4.7	$ 3.5