OTHER FINANCIAL INFORMATION - Unbilled Receivables and Deferred Revenues from Contracts with Customers (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Apr. 03, 2020	Mar. 29, 2019	Apr. 03, 2020	Mar. 29, 2019	Sep. 27, 2019
Other Financial Information [Abstract]
Unbilled receivables - current	$ 276.7		$ 276.7		$ 346.7
Unbilled receivables - long-term	71.6		71.6		35.1
Deferred revenues - current	(798.1)		(798.1)		(766.0)
Deferred revenues - long-term	(74.1)		(74.1)		(73.1)
Total net unbilled receivables (deferred revenues)	(523.9)		(523.9)		$ (457.3)
Decrease in unbilled receivables			33.5
Increase in deferred revenue			33.1
Recognized revenue included in deferred revenue balance	$ 162.4	$ 167.8	$ 476.9	$ 431.2