Equity Changes in Accumulated Other Comprehensive Loss, Tax (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 27, 2025	Sep. 28, 2024	Sep. 30, 2023
Accumulated Other Comprehensive Income (Loss) [Line Items]
AOCI Tax, Attributable to Parent, Beginning Balance	$ 718	$ 595	$ 861
Unrealized gains (losses) arising during the period	(65)	(9)	(355)
Reclassifications of realized net (gains) losses to net income	26	132	89
AOCI reclassifications to comprehensive income, tax	(58)
AOCI Tax, Attributable to Parent, Ending Balance	621	718	595
Market Value Adjustments for Hedges
Accumulated Other Comprehensive Income (Loss) [Line Items]
AOCI Tax, Attributable to Parent, Beginning Balance	71	(64)	(179)
Unrealized gains (losses) arising during the period	(9)	27	12
Reclassifications of realized net (gains) losses to net income	58	108	103
AOCI reclassifications to comprehensive income, tax	0
AOCI Tax, Attributable to Parent, Ending Balance	120	71	(64)
Unrecognized Pension and Postretirement Medical Expense
Accumulated Other Comprehensive Income (Loss) [Line Items]
AOCI Tax, Attributable to Parent, Beginning Balance	531	517	901
Unrealized gains (losses) arising during the period	(53)	(10)	(384)
Reclassifications of realized net (gains) losses to net income	(32)	24	0
AOCI reclassifications to comprehensive income, tax	0
AOCI Tax, Attributable to Parent, Ending Balance	446	531	517
Foreign Currency Translation and Other
Accumulated Other Comprehensive Income (Loss) [Line Items]
AOCI Tax, Attributable to Parent, Beginning Balance	116	142	139
Unrealized gains (losses) arising during the period	(3)	(26)	17
Reclassifications of realized net (gains) losses to net income	0	0	(14)
AOCI reclassifications to comprehensive income, tax	(58)
AOCI Tax, Attributable to Parent, Ending Balance	$ 55	$ 116	$ 142