Components of Net Periodic Benefit Cost (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Dec. 31, 2011	Jan. 01, 2011
Pension Plans
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 70	$ 74
Interest cost	110	103
Expected return on plan assets	(128)	(110)
Amortization of prior year service costs	3	3
Recognized net actuarial loss	77	57
Net periodic benefit cost	132	127
Postretirement Medical Plans
Defined Benefit Plan Disclosure [Line Items]
Service cost	5	5
Interest cost	19	17
Expected return on plan assets	(6)	(6)
Amortization of prior year service costs	(1)	(1)
Recognized net actuarial loss	8	2
Net periodic benefit cost	$ 25	$ 17