Summary of Significant Accounting Policies Goodwill (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Jun. 28, 2020	Jun. 30, 2019	Jun. 28, 2020	Jun. 30, 2019	Sep. 30, 2019	Sep. 29, 2019
Goodwill [Line Items]
Goodwill	$ 3,510.1		$ 3,510.1			$ 3,490.8
Operating Lease, Right-of-Use Asset	8,214.0		8,214.0			0.0
Retained Earnings (Accumulated Deficit)	(8,208.3)		(8,208.3)			(5,771.2)
Operating Lease, Liability, Noncurrent	7,653.6		7,653.6			0.0
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
store occupancy cost	555.5	$ 611.6	1,768.1	$ 1,800.0
Operating Lease, Liability, Noncurrent	7,653.6		7,653.6			0.0
Retained Earnings (Accumulated Deficit)	$ (8,208.3)		$ (8,208.3)			$ (5,771.2)
Accounting Standards Update 2016-02 [Member]
Goodwill [Line Items]
Operating Lease, Right-of-Use Asset					$ 8,400.0
Retained Earnings (Accumulated Deficit)					17.3
Operating Lease, Liability, Noncurrent					9,000.0
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Operating Lease, Liability, Noncurrent					9,000.0
Retained Earnings (Accumulated Deficit)					17.3
Deferred Rent Credit					$ 568.0