Equity Changes in Accumulated Other Comprehensive Loss, Before Tax (Detail) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2023	Oct. 01, 2022	Oct. 02, 2021
Accumulated Other Comprehensive Income (Loss) [Line Items]
AOCI before Tax, Attributable to Parent, Beginning Balance	$ (4,980)	$ (8,224)	$ (10,702)
Unrealized gains (losses) arising during the period	1,491	2,766	1,693
Reclassifications of realized net (gains) losses to net income	(398)	478	785
AOCI before Tax, Attributable to Parent, Ending Balance	(3,887)	(4,980)	(8,224)
Market Value Adjustments for Hedges
Accumulated Other Comprehensive Income (Loss) [Line Items]
AOCI before Tax, Attributable to Parent, Beginning Balance	804	(152)	(191)
Unrealized gains (losses) arising during the period	(101)	1,098	70
Reclassifications of realized net (gains) losses to net income	(444)	(142)	(31)
AOCI before Tax, Attributable to Parent, Ending Balance	259	804	(152)
Unrecognized Pension and Postretirement Medical Expense
Accumulated Other Comprehensive Income (Loss) [Line Items]
AOCI before Tax, Attributable to Parent, Beginning Balance	(3,770)	(7,025)	(9,423)
Unrealized gains (losses) arising during the period	1,594	2,635	1,582
Reclassifications of realized net (gains) losses to net income	4	620	816
AOCI before Tax, Attributable to Parent, Ending Balance	(2,172)	(3,770)	(7,025)
Foreign Currency Translation and Other
Accumulated Other Comprehensive Income (Loss) [Line Items]
AOCI before Tax, Attributable to Parent, Beginning Balance	(2,014)	(1,047)	(1,088)
Unrealized gains (losses) arising during the period	(2)	(967)	41
Reclassifications of realized net (gains) losses to net income	42	0	0
AOCI before Tax, Attributable to Parent, Ending Balance	$ (1,974)	$ (2,014)	$ (1,047)