Changes in Accumulated Other Comprehensive Loss, Net of Tax (Details) - USD ($) $ in Millions		3 Months Ended
		Dec. 28, 2019	Dec. 29, 2018
Accumulated Other Comprehensive Income (Loss) [Line Items]
AOCI, Beginning Balance		$ (6,617)	$ (3,097)
Unrealized gains (losses) arising during the period		23	(2)
Reclassifications of realized net (gains) losses to net income		61	23
AOCI reclassifications to retained earnings, net of tax	[1]		(706)
AOCI, Ending Balance		(6,533)	(3,782)
Investments
Accumulated Other Comprehensive Income (Loss) [Line Items]
AOCI, Beginning Balance		0	15
Unrealized gains (losses) arising during the period		0	0
Reclassifications of realized net (gains) losses to net income		0	0
AOCI reclassifications to retained earnings, net of tax	[1]		(15)
AOCI, Ending Balance		0	0
Cash Flow Hedges
Accumulated Other Comprehensive Income (Loss) [Line Items]
AOCI, Beginning Balance		100	145
Unrealized gains (losses) arising during the period		(61)	21
Reclassifications of realized net (gains) losses to net income		(46)	(30)
AOCI reclassifications to retained earnings, net of tax	[1]		(8)
AOCI, Ending Balance		(7)	128
Unrecognized Pension and  Postretirement Medical  Expense
Accumulated Other Comprehensive Income (Loss) [Line Items]
AOCI, Beginning Balance		(5,746)	(2,633)
Unrealized gains (losses) arising during the period		0	0
Reclassifications of realized net (gains) losses to net income		107	53
AOCI reclassifications to retained earnings, net of tax	[1]		(667)
AOCI, Ending Balance		(5,639)	(3,247)
Foreign Currency Translation and Other
Accumulated Other Comprehensive Income (Loss) [Line Items]
AOCI, Beginning Balance		(971)	(624)
Unrealized gains (losses) arising during the period		84	(23)
Reclassifications of realized net (gains) losses to net income		0	0
AOCI reclassifications to retained earnings, net of tax	[1]		(16)
AOCI, Ending Balance		$ (887)	$ (663)

[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.