Segment Information and Geographic Data - Long-Lived Assets (Details) - USD ($) $ in Millions	Sep. 28, 2019	Sep. 29, 2018
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-lived assets	$ 37,378	$ 41,304
U.S.
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-lived assets	24,711	23,963
China
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-lived assets	9,064	13,268
Other countries
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-lived assets	$ 3,603	$ 4,073