Net Periodic Benefit Cost (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Jun. 27, 2020	Jun. 29, 2019	Jun. 27, 2020	Jun. 29, 2019
Defined Benefit Plan Disclosure [Line Items]
Net Periodic Defined Benefits Expense (Reversal of Expense), Excluding Service Cost Component	$ (3)	$ (27)	$ (8)	$ (77)
Pension Plans
Defined Benefit Plan Disclosure [Line Items]
Service costs	102	89	307	255
Interest costs	133	152	399	441
Expected return on plan assets	(273)	(250)	(819)	(729)
Amortization of previously deferred service costs	3	3	10	10
Recognized net actuarial loss	131	65	393	196
Net Periodic Defined Benefits Expense (Reversal of Expense), Excluding Service Cost Component	(6)	(30)	(17)	(82)
Net periodic benefit cost	96	59	290	173
Postretirement Medical Plans
Defined Benefit Plan Disclosure [Line Items]
Service costs	3	2	8	6
Interest costs	14	17	42	50
Expected return on plan assets	(14)	(14)	(43)	(42)
Amortization of previously deferred service costs	0	0	0	0
Recognized net actuarial loss	3	0	10	0
Net Periodic Defined Benefits Expense (Reversal of Expense), Excluding Service Cost Component	3	3	9	8
Net periodic benefit cost	$ 6	$ 5	$ 17	$ 14