Equity Changes in Accumulated Other Comprehensive Loss, Tax (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Jun. 30, 2018	Jul. 01, 2017	Jun. 30, 2018	Jul. 01, 2017
Accumulated Other Comprehensive Income (Loss) [Line Items]
AOCI Tax, Attributable to Parent, Beginning Balance	$ 1,876	$ 2,188	$ 1,994	$ 2,395
Other Comprehensive Income (Loss) before Reclassifications, Tax	(20)	29	(63)	(145)
Reclassification from AOCI, Current Period, Tax	(30)	(25)	(105)	(58)
AOCI Tax, Attributable to Parent, Ending Balance	1,826	2,192	1,826	2,192
Investments
Accumulated Other Comprehensive Income (Loss) [Line Items]
AOCI Tax, Attributable to Parent, Beginning Balance	(10)	(12)	(7)	(18)
Other Comprehensive Income (Loss) before Reclassifications, Tax	0	(4)	(3)	0
Reclassification from AOCI, Current Period, Tax	0	0	0	2
AOCI Tax, Attributable to Parent, Ending Balance	(10)	(16)	(10)	(16)
Cash Flow Hedges
Accumulated Other Comprehensive Income (Loss) [Line Items]
AOCI Tax, Attributable to Parent, Beginning Balance	41	(50)	46	13
Other Comprehensive Income (Loss) before Reclassifications, Tax	(56)	42	(44)	(66)
Reclassification from AOCI, Current Period, Tax	(6)	15	(23)	60
AOCI Tax, Attributable to Parent, Ending Balance	(21)	7	(21)	7
Unrecognized Pension and Postretirement Medical Expense
Accumulated Other Comprehensive Income (Loss) [Line Items]
AOCI Tax, Attributable to Parent, Beginning Balance	1,778	2,113	1,839	2,208
Other Comprehensive Income (Loss) before Reclassifications, Tax	(2)	0	(5)	(15)
Reclassification from AOCI, Current Period, Tax	(24)	(40)	(82)	(120)
AOCI Tax, Attributable to Parent, Ending Balance	1,752	2,073	1,752	2,073
Foreign Currency Translation and Other
Accumulated Other Comprehensive Income (Loss) [Line Items]
AOCI Tax, Attributable to Parent, Beginning Balance	67	137	116	192
Other Comprehensive Income (Loss) before Reclassifications, Tax	38	(9)	(11)	(64)
Reclassification from AOCI, Current Period, Tax	0	0	0	0
AOCI Tax, Attributable to Parent, Ending Balance	$ 105	$ 128	$ 105	$ 128