Segment Information and Geographic Data - Long-Lived Assets (Details) - USD ($) $ in Millions	Sep. 29, 2018	Sep. 30, 2017
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-lived assets	$ 41,304	$ 33,783
U.S.
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-lived assets	23,963	20,637
China
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-lived assets	13,268	10,211
Other countries
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-lived assets	$ 4,073	$ 2,935