BALANCE SHEET COMPONENTS - Unbilled Receivables and Deferred Revenues from Contracts with Customers (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Mar. 30, 2018	Mar. 31, 2017	Mar. 30, 2018	Mar. 31, 2017	Sep. 29, 2017
Balance Sheet Components [Abstract]
Unbilled receivables - current	$ 311.5		$ 311.5		$ 259.1
Unbilled receivables - long-term (1)	28.2		28.2		10.9
Deferred revenues - current	(766.5)		(766.5)		(755.4)
Deferred revenues - long-term (2)	(9.1)		(9.1)		(7.2)
Total net unbilled receivables (deferred revenues)	(435.9)		(435.9)		$ (492.6)
Increase in deferred revenues net of unbilled receivables			56.7
Recognized revenue included in deferred revenue balance	108.8	$ 127.2	305.2	$ 346.0
Impairment loss on non-current unbilled receivable	$ 0.0	$ 0.0	$ 0.0	$ 17.2