Equity Changes in Accumulated Other Comprehensive Loss, Before Tax (Details) - USD ($) $ in Millions	3 Months Ended
	Dec. 30, 2017	Dec. 31, 2016
Accumulated Other Comprehensive Income (Loss) [Line Items]
AOCI before Tax, Attributable to Parent, Beginning Balance	$ (5,522)	$ (6,374)
Other Comprehensive Income (Loss), before Reclassifications, before Tax	80	347
Reclassification from Accumulated Other Comprehensive Income, Current Period, before Tax	116	38
AOCI before Tax, Attributable to Parent, Ending Balance	(5,326)	(5,989)
Investments
Accumulated Other Comprehensive Income (Loss) [Line Items]
AOCI before Tax, Attributable to Parent, Beginning Balance	15	44
Other Comprehensive Income (Loss), before Reclassifications, before Tax	(1)	(18)
Reclassification from Accumulated Other Comprehensive Income, Current Period, before Tax	0	0
AOCI before Tax, Attributable to Parent, Ending Balance	14	26
Cash Flow Hedges
Accumulated Other Comprehensive Income (Loss) [Line Items]
AOCI before Tax, Attributable to Parent, Beginning Balance	(108)	(38)
Other Comprehensive Income (Loss), before Reclassifications, before Tax	19	506
Reclassification from Accumulated Other Comprehensive Income, Current Period, before Tax	20	(70)
AOCI before Tax, Attributable to Parent, Ending Balance	(69)	398
Unrecognized Pension and Postretirement Medical Expense
Accumulated Other Comprehensive Income (Loss) [Line Items]
AOCI before Tax, Attributable to Parent, Beginning Balance	(4,906)	(5,859)
Other Comprehensive Income (Loss), before Reclassifications, before Tax	0	0
Reclassification from Accumulated Other Comprehensive Income, Current Period, before Tax	96	108
AOCI before Tax, Attributable to Parent, Ending Balance	(4,810)	(5,751)
Foreign Currency Translation and Other
Accumulated Other Comprehensive Income (Loss) [Line Items]
AOCI before Tax, Attributable to Parent, Beginning Balance	(523)	(521)
Other Comprehensive Income (Loss), before Reclassifications, before Tax	62	(141)
Reclassification from Accumulated Other Comprehensive Income, Current Period, before Tax	0	0
AOCI before Tax, Attributable to Parent, Ending Balance	$ (461)	$ (662)