Equity Changes in Accumulated Other Comprehensive Loss, Net of Tax (Details) - USD ($) $ in Millions		12 Months Ended
		Oct. 02, 2021	Oct. 03, 2020	Sep. 28, 2019
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated Other Comprehensive Income (Loss), Net of Tax		$ (8,322)	$ (6,617)	$ (3,097)
Unrealized gains (losses) arising during the period		1,277	(1,923)	(2,886)
Reclassifications of realized net (gains) losses to net income		605	218	72
AOCI reclassifications to retained earnings, net of tax	[1]			(706)
Accumulated Other Comprehensive Income (Loss), Net of Tax		(6,440)	(8,322)	(6,617)
Market Value Adjustments for Hedges
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated Other Comprehensive Income (Loss), Net of Tax		(151)	100	160
Unrealized gains (losses) arising during the period		62	(49)	105
Reclassifications of realized net (gains) losses to net income		(21)	(202)	(142)
AOCI reclassifications to retained earnings, net of tax	[1]			(23)
Accumulated Other Comprehensive Income (Loss), Net of Tax		(110)	(151)	100
Unrecognized Pension and Postretirement Medical Expense
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated Other Comprehensive Income (Loss), Net of Tax		(7,222)	(5,746)	(2,633)
Unrealized gains (losses) arising during the period		1,224	(1,896)	(2,660)
Reclassifications of realized net (gains) losses to net income		626	420	214
AOCI reclassifications to retained earnings, net of tax	[1]			(667)
Accumulated Other Comprehensive Income (Loss), Net of Tax		(5,372)	(7,222)	(5,746)
Foreign Currency Translation and Other
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated Other Comprehensive Income (Loss), Net of Tax		(949)	(971)	(624)
Unrealized gains (losses) arising during the period		(9)	22	(331)
Reclassifications of realized net (gains) losses to net income		0	0	0
AOCI reclassifications to retained earnings, net of tax	[1]			(16)
Accumulated Other Comprehensive Income (Loss), Net of Tax		$ (958)	$ (949)	$ (971)

[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.