Equity Changes in Accumulated Other Comprehensive Loss, Net of Tax (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 28, 2024	Sep. 30, 2023	Oct. 01, 2022
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated Other Comprehensive Income (Loss), Net of Tax	$ (3,292)	$ (4,119)	$ (6,440)
Unrealized gains (losses) arising during the period	23	1,136	1,954
Reclassifications of realized net (gains) losses to net income	(430)	(309)	367
Accumulated Other Comprehensive Income (Loss), Net of Tax	(3,699)	(3,292)	(4,119)
Market Value Adjustments for Hedges
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated Other Comprehensive Income (Loss), Net of Tax	195	625	(110)
Unrealized gains (losses) arising during the period	(85)	(89)	844
Reclassifications of realized net (gains) losses to net income	(358)	(341)	(109)
Accumulated Other Comprehensive Income (Loss), Net of Tax	(248)	195	625
Unrecognized Pension and Postretirement Medical Expense
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated Other Comprehensive Income (Loss), Net of Tax	(1,655)	(2,869)	(5,372)
Unrealized gains (losses) arising during the period	15	1,210	2,027
Reclassifications of realized net (gains) losses to net income	(72)	4	476
Accumulated Other Comprehensive Income (Loss), Net of Tax	(1,712)	(1,655)	(2,869)
Foreign Currency Translation and Other
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated Other Comprehensive Income (Loss), Net of Tax	(1,832)	(1,875)	(958)
Unrealized gains (losses) arising during the period	93	15	(917)
Reclassifications of realized net (gains) losses to net income	0	28	0
Accumulated Other Comprehensive Income (Loss), Net of Tax	$ (1,739)	$ (1,832)	$ (1,875)