Changes in Accumulated Other Comprehensive Loss, Net of Tax (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Jul. 03, 2021	Jun. 27, 2020	Jul. 03, 2021	Jun. 27, 2020
Accumulated Other Comprehensive Income (Loss) [Line Items]
AOCI, Beginning Balance	$ (7,918)	$ (6,637)	$ (8,322)	$ (6,617)
Unrealized gains (losses) arising during the period	(70)	(21)	67	(176)
Reclassifications of realized net (gains) losses to net income	151	41	418	176
AOCI, Ending Balance	(7,837)	(6,617)	(7,837)	(6,617)
Market Value Adjustments for Hedges
Accumulated Other Comprehensive Income (Loss) [Line Items]
AOCI, Beginning Balance	(214)	122	(151)	100
Unrealized gains (losses) arising during the period	(1)	(68)	(33)	32
Reclassifications of realized net (gains) losses to net income	2	(60)	(29)	(138)
AOCI, Ending Balance	(213)	(6)	(213)	(6)
Unrecognized Pension and  Postretirement Medical  Expense
Accumulated Other Comprehensive Income (Loss) [Line Items]
AOCI, Beginning Balance	(6,881)	(5,566)	(7,222)	(5,746)
Unrealized gains (losses) arising during the period	20	(4)	63	(37)
Reclassifications of realized net (gains) losses to net income	149	101	447	314
AOCI, Ending Balance	(6,712)	(5,469)	(6,712)	(5,469)
Foreign Currency Translation and Other
Accumulated Other Comprehensive Income (Loss) [Line Items]
AOCI, Beginning Balance	(823)	(1,193)	(949)	(971)
Unrealized gains (losses) arising during the period	(89)	51	37	(171)
Reclassifications of realized net (gains) losses to net income	0	0	0	0
AOCI, Ending Balance	$ (912)	$ (1,142)	$ (912)	$ (1,142)