Net Periodic Benefit Cost (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Mar. 28, 2020	Mar. 30, 2019	Mar. 28, 2020	Mar. 30, 2019
Defined Benefit Plan Disclosure [Line Items]
Net Periodic Defined Benefits Expense (Reversal of Expense), Excluding Service Cost Component	$ (2)	$ (25)	$ (5)	$ (50)
Pension Plans
Defined Benefit Plan Disclosure [Line Items]
Service costs	102	83	205	166
Interest costs	133	144	266	289
Expected return on plan assets	(273)	(240)	(546)	(479)
Amortization of previously deferred service costs	4	4	7	7
Recognized net actuarial loss	131	67	262	131
Net Periodic Defined Benefits Expense (Reversal of Expense), Excluding Service Cost Component	(5)	(25)	(11)	(52)
Net periodic benefit cost	97	58	194	114
Postretirement Medical Plans
Defined Benefit Plan Disclosure [Line Items]
Service costs	2	2	5	4
Interest costs	14	17	28	33
Expected return on plan assets	(15)	(14)	(29)	(28)
Amortization of previously deferred service costs	0	0	0	0
Recognized net actuarial loss	4	0	7	0
Net Periodic Defined Benefits Expense (Reversal of Expense), Excluding Service Cost Component	3	3	6	5
Net periodic benefit cost	$ 5	$ 5	$ 11	$ 9