Financial Instruments - Notional Amounts and Credit Risk Amounts Associated with Derivative Instruments (Details) - USD ($) $ in Millions	Sep. 26, 2020	Sep. 28, 2019
Derivatives designated as accounting hedges | Foreign exchange contracts
Derivative [Line Items]
Derivatives, notional amount	$ 57,410	$ 61,795
Derivatives, credit risk amount	749	1,798
Derivatives designated as accounting hedges | Interest rate contracts
Derivative [Line Items]
Derivatives, notional amount	20,700	31,250
Derivatives, credit risk amount	1,557	685
Derivatives not designated as accounting hedges | Foreign exchange contracts
Derivative [Line Items]
Derivatives, notional amount	88,636	76,868
Derivatives, credit risk amount	$ 303	$ 323