Financial Instruments - Derivative Instruments at Gross Fair Value (Details) - Level 2 - USD ($) $ in Millions	Mar. 28, 2020	Sep. 28, 2019
Other current assets and other non-current assets | Foreign exchange contracts
Derivative assets:
Fair value of derivative assets	$ 4,228	$ 2,121
Other current assets and other non-current assets | Interest rate contracts
Derivative assets:
Fair value of derivative assets	1,709	685
Other current assets and other non-current assets | Derivatives designated as accounting hedges | Foreign exchange contracts
Derivative assets:
Fair value of derivative assets	2,803	1,798
Other current assets and other non-current assets | Derivatives designated as accounting hedges | Interest rate contracts
Derivative assets:
Fair value of derivative assets	1,709	685
Other current assets and other non-current assets | Derivatives not designated as accounting hedges | Foreign exchange contracts
Derivative assets:
Fair value of derivative assets	1,425	323
Other current assets and other non-current assets | Derivatives not designated as accounting hedges | Interest rate contracts
Derivative assets:
Fair value of derivative assets	0	0
Other current liabilities and other non-current liabilities | Foreign exchange contracts
Derivative liabilities:
Fair value of derivative liabilities	4,163	1,501
Other current liabilities and other non-current liabilities | Interest rate contracts
Derivative liabilities:
Fair value of derivative liabilities	66	105
Other current liabilities and other non-current liabilities | Derivatives designated as accounting hedges | Foreign exchange contracts
Derivative liabilities:
Fair value of derivative liabilities	2,645	1,341
Other current liabilities and other non-current liabilities | Derivatives designated as accounting hedges | Interest rate contracts
Derivative liabilities:
Fair value of derivative liabilities	66	105
Other current liabilities and other non-current liabilities | Derivatives not designated as accounting hedges | Foreign exchange contracts
Derivative liabilities:
Fair value of derivative liabilities	1,518	160
Other current liabilities and other non-current liabilities | Derivatives not designated as accounting hedges | Interest rate contracts
Derivative liabilities:
Fair value of derivative liabilities	$ 0	$ 0