Net Periodic Benefit Cost (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Jun. 29, 2019	Jun. 30, 2018	Jun. 29, 2019	Jun. 30, 2018
Defined Benefit Plan Disclosure [Line Items]
Net Periodic Defined Benefits Expense (Reversal of Expense), Excluding Service Cost Component	$ (27)	$ 0	$ (77)	$ 0
Pension Plans
Defined Benefit Plan Disclosure [Line Items]
Service costs	89	87	255	262
Interest costs	152	122	441	367
Expected return on plan assets	(250)	(225)	(729)	(677)
Amortization of prior-year service costs	3	3	10	11
Recognized net actuarial loss	65	86	196	261
Net Periodic Defined Benefits Expense (Reversal of Expense), Excluding Service Cost Component	(30)	(14)	(82)	(38)
Net periodic benefit cost	59	73	173	224
Postretirement Medical Plans
Defined Benefit Plan Disclosure [Line Items]
Service costs	2	3	6	8
Interest costs	17	15	50	45
Expected return on plan assets	(14)	(13)	(42)	(39)
Amortization of prior-year service costs	0	0	0	0
Recognized net actuarial loss	0	3	0	10
Net Periodic Defined Benefits Expense (Reversal of Expense), Excluding Service Cost Component	3	5	8	16
Net periodic benefit cost	$ 5	$ 8	$ 14	$ 24