Equity Changes in Accumulated Other Comprehensive Loss, Before Tax (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Jun. 29, 2019	Jun. 30, 2018	Jun. 29, 2019	Jun. 30, 2018
Accumulated Other Comprehensive Income (Loss) [Line Items]
AOCI before Tax, Attributable to Parent, Beginning Balance	$ (4,834)	$ (5,221)	$ (4,849)	$ (5,522)
Other Comprehensive Income (Loss), before Reclassifications, before Tax	51	11	9	63
Reclassification from Accumulated Other Comprehensive Income, Current Period, before Tax	14	122	94	371
AOCI reclassifications to retained earnings, before tax			(23)
AOCI before Tax, Attributable to Parent, Ending Balance	(4,769)	(5,088)	(4,769)	(5,088)
Investments
Accumulated Other Comprehensive Income (Loss) [Line Items]
AOCI before Tax, Attributable to Parent, Beginning Balance	(5)	24	24	15
Other Comprehensive Income (Loss), before Reclassifications, before Tax	6	1	1	10
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	1	25	1	25
Cash Flow Hedges
Accumulated Other Comprehensive Income (Loss) [Line Items]
AOCI before Tax, Attributable to Parent, Beginning Balance	62	(197)	177	(108)
Other Comprehensive Income (Loss), before Reclassifications, before Tax	34	296	(21)	150
Reclassification from Accumulated Other Comprehensive Income, Current Period, before Tax	(55)	26	(116)	83
AOCI reclassifications to retained earnings, before tax			1
AOCI before Tax, Attributable to Parent, Ending Balance	41	125	41	125
Unrecognized Pension and Postretirement Medical Expense
Accumulated Other Comprehensive Income (Loss) [Line Items]
AOCI before Tax, Attributable to Parent, Beginning Balance	(4,163)	(4,690)	(4,323)	(4,906)
Other Comprehensive Income (Loss), before Reclassifications, before Tax	(37)	0	(18)	24
Reclassification from Accumulated Other Comprehensive Income, Current Period, before Tax	69	96	210	288
AOCI reclassifications to retained earnings, before tax			0
AOCI before Tax, Attributable to Parent, Ending Balance	(4,131)	(4,594)	(4,131)	(4,594)
Foreign Currency Translation and Other
Accumulated Other Comprehensive Income (Loss) [Line Items]
AOCI before Tax, Attributable to Parent, Beginning Balance	(728)	(358)	(727)	(523)
Other Comprehensive Income (Loss), before Reclassifications, before Tax	48	(286)	47	(121)
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	$ (680)	$ (644)	$ (680)	$ (644)