Changes in Accumulated Other Comprehensive Loss, Net of Tax (Details) - USD ($) $ in Millions		3 Months Ended		9 Months Ended
		Jun. 27, 2020	Jun. 29, 2019	Jun. 27, 2020	Jun. 29, 2019
Accumulated Other Comprehensive Income (Loss) [Line Items]
AOCI, Beginning Balance		$ (6,637)	$ (3,786)	$ (6,617)	$ (3,097)
Unrealized gains (losses) arising during the period		(21)	54	(176)	10
Reclassifications of realized net (gains) losses to net income		41	11	176	72
AOCI reclassifications to retained earnings, net of tax	[1]				(706)
AOCI, Ending Balance		(6,617)	(3,721)	(6,617)	(3,721)
Accumulated Net Gain (Loss) from Market Value Adjustments
Accumulated Other Comprehensive Income (Loss) [Line Items]
AOCI, Beginning Balance	[2]	122	44	100	160
Unrealized gains (losses) arising during the period	[2]	(68)	30	32	(16)
Reclassifications of realized net (gains) losses to net income	[2]	(60)	(42)	(138)	(89)
AOCI reclassifications to retained earnings, net of tax	[1],[2]				(23)
AOCI, Ending Balance	[2]	(6)	32	(6)	32
Unrecognized Pension and  Postretirement Medical  Expense
Accumulated Other Comprehensive Income (Loss) [Line Items]
AOCI, Beginning Balance		(5,566)	(3,179)	(5,746)	(2,633)
Unrealized gains (losses) arising during the period		(4)	(29)	(37)	(16)
Reclassifications of realized net (gains) losses to net income		101	53	314	161
AOCI reclassifications to retained earnings, net of tax	[1]				(667)
AOCI, Ending Balance		(5,469)	(3,155)	(5,469)	(3,155)
Foreign Currency Translation and Other
Accumulated Other Comprehensive Income (Loss) [Line Items]
AOCI, Beginning Balance		(1,193)	(651)	(971)	(624)
Unrealized gains (losses) arising during the period		51	53	(171)	42
Reclassifications of realized net (gains) losses to net income		0	0	0	0
AOCI reclassifications to retained earnings, net of tax	[1]				(16)
AOCI, Ending Balance		$ (1,142)	$ (598)	$ (1,142)	$ (598)

[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.

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