Segment Information and Geographic Data - Net Sales (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Sep. 26, 2020	Jun. 27, 2020	Mar. 28, 2020	Dec. 28, 2019	Sep. 28, 2019	Jun. 29, 2019	Mar. 30, 2019	Dec. 29, 2018	Sep. 26, 2020	Sep. 28, 2019	Sep. 29, 2018
Revenues from External Customers and Long-Lived Assets [Line Items]
Net sales	$ 64,698	$ 59,685	$ 58,313	$ 91,819	$ 64,040	$ 53,809	$ 58,015	$ 84,310	$ 274,515	$ 260,174	$ 265,595
U.S.
Revenues from External Customers and Long-Lived Assets [Line Items]
Net sales									109,197	102,266	98,061
China
Revenues from External Customers and Long-Lived Assets [Line Items]
Net sales									40,308	43,678	51,942
Other countries
Revenues from External Customers and Long-Lived Assets [Line Items]
Net sales									$ 125,010	$ 114,230	$ 115,592