Equity Changes in Accumulated Other Comprehensive Loss, Before Tax (Details) - USD ($) $ in Millions	3 Months Ended
	Dec. 29, 2018	Dec. 30, 2017
Accumulated Other Comprehensive Income (Loss) [Line Items]
AOCI before Tax, Attributable to Parent, Beginning Balance	$ (4,849)	$ (5,522)
Other Comprehensive Income (Loss), before Reclassifications, before Tax	11	80
Reclassification from Accumulated Other Comprehensive Income, Current Period, before Tax	30	116
AOCI reclassifications to retained earnings, before tax	(23)
AOCI before Tax, Attributable to Parent, Ending Balance	(4,831)	(5,326)
Investments
Accumulated Other Comprehensive Income (Loss) [Line Items]
AOCI before Tax, Attributable to Parent, Beginning Balance	24	15
Other Comprehensive Income (Loss), before Reclassifications, before Tax	0	(1)
Reclassification from Accumulated Other Comprehensive Income, Current Period, before Tax	0	0
AOCI reclassifications to retained earnings, before tax	(24)
AOCI before Tax, Attributable to Parent, Ending Balance	0	14
Cash Flow Hedges
Accumulated Other Comprehensive Income (Loss) [Line Items]
AOCI before Tax, Attributable to Parent, Beginning Balance	177	(108)
Other Comprehensive Income (Loss), before Reclassifications, before Tax	27	19
Reclassification from Accumulated Other Comprehensive Income, Current Period, before Tax	(39)	20
AOCI reclassifications to retained earnings, before tax	1
AOCI before Tax, Attributable to Parent, Ending Balance	166	(69)
Unrecognized Pension and Postretirement Medical Expense
Accumulated Other Comprehensive Income (Loss) [Line Items]
AOCI before Tax, Attributable to Parent, Beginning Balance	(4,323)	(4,906)
Other Comprehensive Income (Loss), before Reclassifications, before Tax	0	0
Reclassification from Accumulated Other Comprehensive Income, Current Period, before Tax	69	96
AOCI reclassifications to retained earnings, before tax	0
AOCI before Tax, Attributable to Parent, Ending Balance	(4,254)	(4,810)
Foreign Currency Translation and Other
Accumulated Other Comprehensive Income (Loss) [Line Items]
AOCI before Tax, Attributable to Parent, Beginning Balance	(727)	(523)
Other Comprehensive Income (Loss), before Reclassifications, before Tax	(16)	62
Reclassification from Accumulated Other Comprehensive Income, Current Period, before Tax	0	0
AOCI reclassifications to retained earnings, before tax	0
AOCI before Tax, Attributable to Parent, Ending Balance	$ (743)	$ (461)