Equity Changes in Accumulated Other Comprehensive Loss, 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 Tax, Attributable to Parent, Beginning Balance	$ 1,049	$ 1,922	$ 1,752	$ 1,994
Other Comprehensive Income (Loss) before Reclassifications, Tax	11	(14)	(2)	(43)
Reclassification from AOCI, Current Period, Tax	(12)	(32)	(19)	(75)
AOCI reclassifications to retained earnings, tax			(683)
AOCI Tax, Attributable to Parent, Ending Balance	1,048	1,876	1,048	1,876
Investments
Accumulated Other Comprehensive Income (Loss) [Line Items]
AOCI Tax, Attributable to Parent, Beginning Balance	0	(7)	(9)	(7)
Other Comprehensive Income (Loss) before Reclassifications, Tax	1	(3)	1	(3)
Reclassification from AOCI, Current Period, Tax	0	0	0	0
AOCI reclassifications to retained earnings, tax			9
AOCI Tax, Attributable to Parent, Ending Balance	1	(10)	1	(10)
Cash Flow Hedges
Accumulated Other Comprehensive Income (Loss) [Line Items]
AOCI Tax, Attributable to Parent, Beginning Balance	(38)	25	(32)	46
Other Comprehensive Income (Loss) before Reclassifications, Tax	19	25	13	12
Reclassification from AOCI, Current Period, Tax	5	(9)	14	(17)
AOCI reclassifications to retained earnings, tax			(9)
AOCI Tax, Attributable to Parent, Ending Balance	(14)	41	(14)	41
Unrecognized Pension and Postretirement Medical Expense
Accumulated Other Comprehensive Income (Loss) [Line Items]
AOCI Tax, Attributable to Parent, Beginning Balance	1,007	1,804	1,690	1,839
Other Comprehensive Income (Loss) before Reclassifications, Tax	(6)	(3)	(6)	(3)
Reclassification from AOCI, Current Period, Tax	(17)	(23)	(33)	(58)
AOCI reclassifications to retained earnings, tax			(667)
AOCI Tax, Attributable to Parent, Ending Balance	984	1,778	984	1,778
Foreign Currency Translation and Other
Accumulated Other Comprehensive Income (Loss) [Line Items]
AOCI Tax, Attributable to Parent, Beginning Balance	80	100	103	116
Other Comprehensive Income (Loss) before Reclassifications, Tax	(3)	(33)	(10)	(49)
Reclassification from AOCI, Current Period, Tax	0	0	0	0
AOCI reclassifications to retained earnings, tax			(16)
AOCI Tax, Attributable to Parent, Ending Balance	$ 77	$ 67	$ 77	$ 67