Pension and Other Benefit Programs - Net Periodic Benefit Cost (Detail) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2017	Oct. 01, 2016	Oct. 03, 2015
Pension Plans
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 368	$ 318	$ 332
Interest cost	447	458	521
Expected return on plan assets	(874)	(747)	(711)
Amortization of prior year service costs	12	14	16
Recognized net actuarial loss	405	242	247
Net periodic benefit cost	358	285	405
Postretirement Medical Plans
Defined Benefit Plan Disclosure [Line Items]
Service cost	11	11	14
Interest cost	56	61	68
Expected return on plan assets	(49)	(45)	(39)
Amortization of prior year service costs	0	(1)	(1)
Recognized net actuarial loss	17	8	10
Net periodic benefit cost	$ 35	$ 34	$ 52