OTHER FINANCIAL INFORMATION - Unbilled Receivables and Deferred Revenues from Contracts with Customers (Details) - USD ($) $ in Millions	3 Months Ended
	Jan. 01, 2021	Jan. 03, 2020	Oct. 02, 2020
Other Financial Information [Abstract]
Unbilled receivables - current	$ 292.7		$ 306.2
Unbilled receivables - long-term	94.1		68.6
Deferred revenues - current	(845.7)		(782.2)
Deferred revenues - long-term	(76.3)		(68.5)
Total net unbilled receivables (deferred revenues)	(535.2)		$ (475.9)
Increase in unbilled receivables	12.0
Decrease in deferred revenue	71.3
Recognized revenue included in deferred revenue balance	$ 276.4	$ 314.5