Equity Changes in Accumulated Other Comprehensive Loss, Tax (Details) - USD ($) $ in Millions		3 Months Ended
		Dec. 28, 2019	Dec. 29, 2018
Accumulated Other Comprehensive Income (Loss) [Line Items]
AOCI Tax, Attributable to Parent, Beginning Balance		$ 1,842	$ 1,752
Other Comprehensive Income (Loss) before Reclassifications, Tax		22	(13)
Reclassification from AOCI, Current Period, Tax		(18)	(7)
AOCI reclassifications to retained earnings, tax	[1]		(683)
AOCI Tax, Attributable to Parent, Ending Balance		1,846	1,049
Investments
Accumulated Other Comprehensive Income (Loss) [Line Items]
AOCI Tax, Attributable to Parent, Beginning Balance		0	(9)
Other Comprehensive Income (Loss) before Reclassifications, Tax		0	0
Reclassification from AOCI, Current Period, Tax		0	0
AOCI reclassifications to retained earnings, tax	[1]		9
AOCI Tax, Attributable to Parent, Ending Balance		0	0
Cash Flow Hedges
Accumulated Other Comprehensive Income (Loss) [Line Items]
AOCI Tax, Attributable to Parent, Beginning Balance		(29)	(32)
Other Comprehensive Income (Loss) before Reclassifications, Tax		20	(6)
Reclassification from AOCI, Current Period, Tax		14	9
AOCI reclassifications to retained earnings, tax	[1]		(9)
AOCI Tax, Attributable to Parent, Ending Balance		5	(38)
Unrecognized Pension and  Postretirement Medical  Expense
Accumulated Other Comprehensive Income (Loss) [Line Items]
AOCI Tax, Attributable to Parent, Beginning Balance		1,756	1,690
Other Comprehensive Income (Loss) before Reclassifications, Tax		0	0
Reclassification from AOCI, Current Period, Tax		(32)	(16)
AOCI reclassifications to retained earnings, tax	[1]		(667)
AOCI Tax, Attributable to Parent, Ending Balance		1,724	1,007
Foreign Currency Translation and Other
Accumulated Other Comprehensive Income (Loss) [Line Items]
AOCI Tax, Attributable to Parent, Beginning Balance		115	103
Other Comprehensive Income (Loss) before Reclassifications, Tax		2	(7)
Reclassification from AOCI, Current Period, Tax		0	0
AOCI reclassifications to retained earnings, tax	[1]		(16)
AOCI Tax, Attributable to Parent, Ending Balance		$ 117	$ 80

[1] At the beginning of fiscal 2019, the Company adopted new FASB accounting guidance, Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income, and reclassified $691 million from AOCI to retained earnings.In addition, at the beginning of fiscal 2019, the Company adopted new FASB accounting guidance, Recognition and Measurement of Financial Assets and Liabilities, and reclassified $24 million ($15 million after tax) of market value adjustments on investments previously recorded in AOCI to retained earnings.