Equity Changes in Accumulated Other Comprehensive Loss, Before Tax (Details) - USD ($) $ in Millions	3 Months Ended
	Dec. 31, 2022	Jan. 01, 2022
Accumulated Other Comprehensive Income (Loss) [Line Items]
AOCI before Tax, Attributable to Parent, Beginning Balance	$ (4,980)	$ (8,224)
Unrealized gains (losses) arising during the period	(329)	97
Reclassifications of realized net (gains) losses to net income	(175)	137
AOCI before Tax, Attributable to Parent, Ending Balance	(5,484)	(7,990)
Market Value Adjustments for Hedges
Accumulated Other Comprehensive Income (Loss) [Line Items]
AOCI before Tax, Attributable to Parent, Beginning Balance	804	(152)
Unrealized gains (losses) arising during the period	(475)	87
Reclassifications of realized net (gains) losses to net income	(218)	(18)
AOCI before Tax, Attributable to Parent, Ending Balance	111	(83)
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)
Unrealized gains (losses) arising during the period	0	47
Reclassifications of realized net (gains) losses to net income	1	155
AOCI before Tax, Attributable to Parent, Ending Balance	(3,769)	(6,823)
Foreign Currency Translation and Other
Accumulated Other Comprehensive Income (Loss) [Line Items]
AOCI before Tax, Attributable to Parent, Beginning Balance	(2,014)	(1,047)
Unrealized gains (losses) arising during the period	146	(37)
Reclassifications of realized net (gains) losses to net income	42	0
AOCI before Tax, Attributable to Parent, Ending Balance	$ (1,826)	$ (1,084)