Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020	Sep. 30, 2020
Accumulated other comprehensive income [Roll Forward]
Beginning balance			$ 8,447
Ending balance	$ 9,339	$ 7,878	9,339	$ 7,878
Accumulated other comprehensive income (loss)	(1,307)	(1,699)	(1,307)	(1,699)	$ (1,577)
Foreign currency translation [Member]
Accumulated other comprehensive income [Roll Forward]
Beginning balance	(542)	(977)	(711)	(794)
Other comprehensive income (loss), foreign currency translation, net of tax of $(1), $17, $5 and $10, respectively	(6)	135	163	(48)
Ending balance	(548)	(842)	(548)	(842)
Pension and post retirement [Member]
Accumulated other comprehensive income [Roll Forward]
Beginning balance	(810)	(870)	(864)	(928)
Amortization of deferred actuarial losses into earnings, net of tax of $(8), $(9), $(24) and $(26), respectively	27	29	81	87
Ending balance	(783)	(841)	(783)	(841)
Cash Flow Hedges [Member]
Accumulated other comprehensive income [Roll Forward]
Beginning balance	30	(56)	(2)	0
Deferral of gains (losses) arising during the period, net of tax of $(2), $(11), $(15) and $6, respectively	7	33	50	(20)
Reclassification of realized gains (losses) to sales and cost of sales, net of tax of $3, $(2), $7 and $(1), respectively	(13)	7	(24)	4
Ending balance	$ 24	$ (16)	$ 24	$ (16)