Net Periodic Benefit Cost (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Dec. 28, 2013	Dec. 29, 2012
Pension Plans
Defined Benefit Plan Disclosure [Line Items]
Service costs	$ 71	$ 86
Interest costs	122	109
Expected return on plan assets	(161)	(151)
Amortization of prior-year service costs	4	2
Recognized net actuarial loss/(gain)	36	104
Net periodic benefit cost	72	150
Postretirement Medical Plans
Defined Benefit Plan Disclosure [Line Items]
Service costs	3	4
Interest costs	16	17
Expected return on plan assets	(9)	(8)
Amortization of prior-year service costs	0	(1)
Recognized net actuarial loss/(gain)	(2)	10
Net periodic benefit cost	$ 8	$ 22