Changes in Accumulated Other Comprehensive Loss, Net of Tax (Details) - USD ($) $ in Millions		3 Months Ended		6 Months Ended
		Mar. 30, 2019	Mar. 31, 2018	Mar. 30, 2019	Mar. 31, 2018
Accumulated Other Comprehensive Income (Loss) [Line Items]
AOCI, Beginning Balance		$ (3,782)	$ (3,404)	$ (3,097)	$ (3,528)
Unrealized gains (losses) arising during the period		(42)	(42)	(44)	9
Reclassifications of realized net (gains) losses to net income		38	101	61	174
AOCI reclassifications to retained earnings, net of tax	[1]			(706)
AOCI, Ending Balance		(3,786)	(3,345)	(3,786)	(3,345)
Investments
Accumulated Other Comprehensive Income (Loss) [Line Items]
AOCI, Beginning Balance		0	7	15	8
Unrealized gains (losses) arising during the period		(4)	7	(4)	6
Reclassifications of realized net (gains) losses to net income		0	0	0	0
AOCI reclassifications to retained earnings, net of tax	[1]			(15)
AOCI, Ending Balance		(4)	14	(4)	14
Cash Flow Hedges
Accumulated Other Comprehensive Income (Loss) [Line Items]
AOCI, Beginning Balance		128	(44)	145	(62)
Unrealized gains (losses) arising during the period		(63)	(140)	(42)	(134)
Reclassifications of realized net (gains) losses to net income		(17)	28	47	40
AOCI reclassifications to retained earnings, net of tax	[1]			(8)
AOCI, Ending Balance		48	(156)	48	(156)
Unrecognized Pension and Postretirement Medical Expense
Accumulated Other Comprehensive Income (Loss) [Line Items]
AOCI, Beginning Balance		(3,247)	(3,006)	(2,633)	(3,067)
Unrealized gains (losses) arising during the period		13	21	13	21
Reclassifications of realized net (gains) losses to net income		55	73	(108)	134
AOCI reclassifications to retained earnings, net of tax	[1]			(667)
AOCI, Ending Balance		(3,179)	(2,912)	(3,179)	(2,912)
Foreign Currency Translation and Other
Accumulated Other Comprehensive Income (Loss) [Line Items]
AOCI, Beginning Balance		(663)	(361)	(624)	(407)
Unrealized gains (losses) arising during the period		12	70	(11)	116
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		$ (651)	$ (291)	$ (651)	$ (291)

[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.