Retirement Plans - Defined Benefit Pension Plan Asset Categories and Fair Value Hierarchy (Details) - USD ($) $ in Millions	Sep. 27, 2019	Sep. 28, 2018	Sep. 29, 2017
Non-U.S. Plans
Summary of asset fair value
Fair value of plan assets	$ 1,489	$ 1,390	$ 1,402
Non-U.S. Plans | Fair Value
Summary of asset fair value
Fair value of plan assets	1,489	1,390
Non-U.S. Plans | Subtotal | Level 2
Summary of asset fair value
Fair value of plan assets	1,312	1,264
Non-U.S. Plans | Subtotal | Level 3
Summary of asset fair value
Fair value of plan assets	157	120
Non-U.S. Plans | Subtotal | Fair Value
Summary of asset fair value
Fair value of plan assets	1,469	1,384
Non-U.S. Plans | Commingled equity funds | Level 2
Summary of asset fair value
Fair value of plan assets	339	397
Non-U.S. Plans | Commingled equity funds | Fair Value
Summary of asset fair value
Fair value of plan assets	339	397
Non-U.S. Plans | Government bonds | Level 2
Summary of asset fair value
Fair value of plan assets	315	213
Non-U.S. Plans | Government bonds | Fair Value
Summary of asset fair value
Fair value of plan assets	315	213
Non-U.S. Plans | Corporate bonds | Level 2
Summary of asset fair value
Fair value of plan assets	137	6
Non-U.S. Plans | Corporate bonds | Fair Value
Summary of asset fair value
Fair value of plan assets	137	6
Non-U.S. Plans | Commingled bond funds | Level 2
Summary of asset fair value
Fair value of plan assets	359	464
Non-U.S. Plans | Commingled bond funds | Fair Value
Summary of asset fair value
Fair value of plan assets	359	464
Non-U.S. Plans | Other | Level 2
Summary of asset fair value
Fair value of plan assets	162	184
Non-U.S. Plans | Other | Level 3
Summary of asset fair value
Fair value of plan assets	157	120
Non-U.S. Plans | Other | Fair Value
Summary of asset fair value
Fair value of plan assets	319	304
Non-U.S. Plans | Items to reconcile to fair value of plan assets | Fair Value
Summary of asset fair value
Fair value of plan assets	20	6
U.S. Plans
Summary of asset fair value
Fair value of plan assets	937	917	$ 963
U.S. Plans | Fair Value
Summary of asset fair value
Fair value of plan assets	937	917
U.S. Plans | Subtotal | Level 1
Summary of asset fair value
Fair value of plan assets		485
U.S. Plans | Subtotal | Level 2
Summary of asset fair value
Fair value of plan assets	936	426
U.S. Plans | Subtotal | Fair Value
Summary of asset fair value
Fair value of plan assets	936	911
U.S. Plans | Non-U.S. equity securities | Level 1
Summary of asset fair value
Fair value of plan assets		220
U.S. Plans | Non-U.S. equity securities | Fair Value
Summary of asset fair value
Fair value of plan assets		220
U.S. Plans | U.S. equity securities | Level 1
Summary of asset fair value
Fair value of plan assets		265
U.S. Plans | U.S. equity securities | Fair Value
Summary of asset fair value
Fair value of plan assets		265
U.S. Plans | Commingled equity funds | Level 2
Summary of asset fair value
Fair value of plan assets	385
U.S. Plans | Commingled equity funds | Fair Value
Summary of asset fair value
Fair value of plan assets	385
U.S. Plans | Government bonds | Level 2
Summary of asset fair value
Fair value of plan assets		45
U.S. Plans | Government bonds | Fair Value
Summary of asset fair value
Fair value of plan assets		45
U.S. Plans | Corporate bonds | Level 2
Summary of asset fair value
Fair value of plan assets		283
U.S. Plans | Corporate bonds | Fair Value
Summary of asset fair value
Fair value of plan assets		283
U.S. Plans | Commingled bond funds | Level 2
Summary of asset fair value
Fair value of plan assets	540	87
U.S. Plans | Commingled bond funds | Fair Value
Summary of asset fair value
Fair value of plan assets	540	87
U.S. Plans | Other | Level 2
Summary of asset fair value
Fair value of plan assets	11	11
U.S. Plans | Other | Fair Value
Summary of asset fair value
Fair value of plan assets	11	11
U.S. Plans | Items to reconcile to fair value of plan assets | Fair Value
Summary of asset fair value
Fair value of plan assets	$ 1	$ 6