Income Taxes (Income Tax Expense Reconciliation) (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 28, 2018	Sep. 29, 2017	Sep. 30, 2016
Income Tax Disclosure [Abstract]
Tax expense at United States statutory rate	$ 327.4	$ 439.9	$ 420.2
Foreign tax rate difference	(111.9)	(174.6)	(160.8)
Effective Income Tax Rate Reconciliation, Repatriation of Foreign Earnings, Amount	224.6	0.0	0.0
Effective Income Tax Rate Reconciliation, Other Adjustments, Amount	(25.6)	0.0	0.0
Effective Income Tax Rate Reconciliation, Change in Enacted Tax Rate, Amount	18.3	0.0	0.0
Research and development credits	(19.9)	(16.3)	(33.7)
Change in tax reserve	6.7	12.6	(2.5)
Domestic production activities deduction	(13.9)	(19.8)	(19.1)
Other, net	8.0	5.0	1.3
Provision for income taxes	$ 413.7	$ 246.8	$ 205.4