Equity Changes in Accumulated Other Comprehensive Loss, Net of Tax (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2023	Oct. 01, 2022	Oct. 02, 2021
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated Other Comprehensive Income (Loss), Net of Tax	$ (4,119)	$ (6,440)	$ (8,322)
Unrealized gains (losses) arising during the period	1,136	1,954	1,277
Reclassifications of realized net (gains) losses to net income	(309)	367	605
Accumulated Other Comprehensive Income (Loss), Net of Tax	(3,292)	(4,119)	(6,440)
Market Value Adjustments for Hedges
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated Other Comprehensive Income (Loss), Net of Tax	625	(110)	(151)
Unrealized gains (losses) arising during the period	(89)	844	62
Reclassifications of realized net (gains) losses to net income	(341)	(109)	(21)
Accumulated Other Comprehensive Income (Loss), Net of Tax	195	625	(110)
Unrecognized Pension and Postretirement Medical Expense
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated Other Comprehensive Income (Loss), Net of Tax	(2,869)	(5,372)	(7,222)
Unrealized gains (losses) arising during the period	1,210	2,027	1,224
Reclassifications of realized net (gains) losses to net income	4	476	626
Accumulated Other Comprehensive Income (Loss), Net of Tax	(1,655)	(2,869)	(5,372)
Foreign Currency Translation and Other
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated Other Comprehensive Income (Loss), Net of Tax	(1,875)	(958)	(949)
Unrealized gains (losses) arising during the period	15	(917)	(9)
Reclassifications of realized net (gains) losses to net income	28	0	0
Accumulated Other Comprehensive Income (Loss), Net of Tax	$ (1,832)	$ (1,875)	$ (958)