Equity Changes in Accumulated Other Comprehensive Loss, Tax (Details) - USD ($) $ in Millions		3 Months Ended
		Jan. 02, 2021	Dec. 28, 2019
Accumulated Other Comprehensive Income (Loss) [Line Items]
AOCI Tax, Attributable to Parent, Beginning Balance		$ 2,380	$ 1,842
Other Comprehensive Income (Loss) before Reclassifications, Tax		38	22
Reclassification from AOCI, Current Period, Tax		(36)	(18)
AOCI Tax, Attributable to Parent, Ending Balance		2,382	1,846
Accumulated Net Gain (Loss) from Market Value Adjustments
Accumulated Other Comprehensive Income (Loss) [Line Items]
AOCI Tax, Attributable to Parent, Beginning Balance	[1]	40	(29)
Other Comprehensive Income (Loss) before Reclassifications, Tax	[1]	46	20
Reclassification from AOCI, Current Period, Tax	[1]	9	14
AOCI Tax, Attributable to Parent, Ending Balance	[1]	95	5
Unrecognized Pension and  Postretirement Medical  Expense
Accumulated Other Comprehensive Income (Loss) [Line Items]
AOCI Tax, Attributable to Parent, Beginning Balance		2,201	1,756
Other Comprehensive Income (Loss) before Reclassifications, Tax		(1)	0
Reclassification from AOCI, Current Period, Tax		(45)	(32)
AOCI Tax, Attributable to Parent, Ending Balance		2,155	1,724
Foreign Currency Translation and Other
Accumulated Other Comprehensive Income (Loss) [Line Items]
AOCI Tax, Attributable to Parent, Beginning Balance		139	115
Other Comprehensive Income (Loss) before Reclassifications, Tax		(7)	2
Reclassification from AOCI, Current Period, Tax		0	0
AOCI Tax, Attributable to Parent, Ending Balance		$ 132	$ 117

[1] Primarily reflects market value adjustments for cash flow hedges.