Segment Information and Geographic Data - Long-Lived Assets (Details) - USD ($) $ in Millions	Sep. 26, 2020	Sep. 28, 2019
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-lived assets	$ 36,766	$ 37,378
U.S.
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-lived assets	25,890	24,711
China
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-lived assets	7,256	9,064
Other countries
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-lived assets	$ 3,620	$ 3,603