Financial Instruments - Notional Amounts and Credit Risk Amounts Associated with Derivative Instruments (Details) - USD ($) $ in Millions	Sep. 28, 2019	Sep. 29, 2018
Derivatives designated as accounting hedges | Foreign exchange contracts
Derivative [Line Items]
Derivative, notional amount	$ 61,795	$ 65,368
Derivative, credit risk amount	1,798	1,015
Derivatives designated as accounting hedges | Interest rate contracts
Derivative [Line Items]
Derivative, notional amount	31,250	33,250
Derivative, credit risk amount	685	0
Derivatives not designated as accounting hedges | Foreign exchange contracts
Derivative [Line Items]
Derivative, notional amount	76,868	63,062
Derivative, credit risk amount	$ 323	$ 259