Other Financial Information - Contracts with Customers (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 27, 2019	Sep. 28, 2018
Other Financial Information [Abstract]
Unbilled receivables - current	$ 346.7	$ 362.8
Unbilled receivables - long-term (1)	35.1	36.3
Deferred revenues - current	(766.0)	(729.7)
Deferred revenues - long-term (2)	(73.1)	(38.6)
Total net unbilled receivables (deferred revenues)	(457.3)	(369.2)
Decrease in unbilled receivables	(17.3)
Increase in deferred revenue	70.8
Deferred revenues recognized	$ 616.9	$ 407.0