Equity Changes in Accumulated Other Comprehensive Loss, Tax (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2023	Oct. 01, 2022	Oct. 02, 2021
Accumulated Other Comprehensive Income (Loss) [Line Items]
AOCI Tax, Attributable to Parent, Beginning Balance	$ 861	$ 1,784	$ 2,380
Unrealized gains (losses) arising during the period	(355)	(812)	(416)
Reclassifications of realized net (gains) losses to net income	89	(111)	(180)
AOCI Tax, Attributable to Parent, Ending Balance	595	861	1,784
Market Value Adjustments for Hedges
Accumulated Other Comprehensive Income (Loss) [Line Items]
AOCI Tax, Attributable to Parent, Beginning Balance	(179)	42	40
Unrealized gains (losses) arising during the period	12	(254)	(8)
Reclassifications of realized net (gains) losses to net income	103	33	10
AOCI Tax, Attributable to Parent, Ending Balance	(64)	(179)	42
Unrecognized Pension and Postretirement Medical Expense
Accumulated Other Comprehensive Income (Loss) [Line Items]
AOCI Tax, Attributable to Parent, Beginning Balance	901	1,653	2,201
Unrealized gains (losses) arising during the period	(384)	(608)	(358)
Reclassifications of realized net (gains) losses to net income	0	(144)	(190)
AOCI Tax, Attributable to Parent, Ending Balance	517	901	1,653
Foreign Currency Translation and Other
Accumulated Other Comprehensive Income (Loss) [Line Items]
AOCI Tax, Attributable to Parent, Beginning Balance	139	89	139
Unrealized gains (losses) arising during the period	17	50	(50)
Reclassifications of realized net (gains) losses to net income	(14)	0	0
AOCI Tax, Attributable to Parent, Ending Balance	$ 142	$ 139	$ 89