Equity Changes in Accumulated Other Comprehensive Loss, Before 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 before Tax, Attributable to Parent, Beginning Balance	$ (4,831)	$ (5,326)	$ (4,849)	$ (5,522)
Other Comprehensive Income (Loss), before Reclassifications, before Tax	(53)	(28)	(42)	52
Reclassification from Accumulated Other Comprehensive Income, Current Period, before Tax	50	133	80	249
AOCI reclassifications to retained earnings, before tax			(23)
AOCI before Tax, Attributable to Parent, Ending Balance	(4,834)	(5,221)	(4,834)	(5,221)
Investments
Accumulated Other Comprehensive Income (Loss) [Line Items]
AOCI before Tax, Attributable to Parent, Beginning Balance	0	14	24	15
Other Comprehensive Income (Loss), before Reclassifications, before Tax	(5)	10	(5)	9
Reclassification from Accumulated Other Comprehensive Income, Current Period, before Tax	0	0	0	0
AOCI reclassifications to retained earnings, before tax			(24)
AOCI before Tax, Attributable to Parent, Ending Balance	(5)	24	(5)	24
Cash Flow Hedges
Accumulated Other Comprehensive Income (Loss) [Line Items]
AOCI before Tax, Attributable to Parent, Beginning Balance	166	(69)	177	(108)
Other Comprehensive Income (Loss), before Reclassifications, before Tax	(82)	(165)	(55)	(146)
Reclassification from Accumulated Other Comprehensive Income, Current Period, before Tax	(22)	37	(61)	57
AOCI reclassifications to retained earnings, before tax			1
AOCI before Tax, Attributable to Parent, Ending Balance	62	(197)	62	(197)
Unrecognized Pension and Postretirement Medical Expense
Accumulated Other Comprehensive Income (Loss) [Line Items]
AOCI before Tax, Attributable to Parent, Beginning Balance	(4,254)	(4,810)	(4,323)	(4,906)
Other Comprehensive Income (Loss), before Reclassifications, before Tax	19	24	19	24
Reclassification from Accumulated Other Comprehensive Income, Current Period, before Tax	72	96	141	192
AOCI reclassifications to retained earnings, before tax			0
AOCI before Tax, Attributable to Parent, Ending Balance	(4,163)	(4,690)	(4,163)	(4,690)
Foreign Currency Translation and Other
Accumulated Other Comprehensive Income (Loss) [Line Items]
AOCI before Tax, Attributable to Parent, Beginning Balance	(743)	(461)	(727)	(523)
Other Comprehensive Income (Loss), before Reclassifications, before Tax	15	103	(1)	165
Reclassification from Accumulated Other Comprehensive Income, Current Period, before Tax	0	0	0	0
AOCI reclassifications to retained earnings, before tax			0
AOCI before Tax, Attributable to Parent, Ending Balance	$ (728)	$ (358)	$ (728)	$ (358)