Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Mar. 31, 2022	Mar. 31, 2021	Mar. 31, 2022	Mar. 31, 2021	Sep. 30, 2021
Accumulated other comprehensive income [Roll Forward]
Beginning balance			$ 9,923
Other Comprehensive Income (Loss) Net of Tax, Period Change [Abstract]
Ending balance	$ 10,614	$ 9,180	10,614	$ 9,180
Accumulated other comprehensive income (loss)	(957)	(1,322)	(957)	(1,322)	$ (872)
Accumulated other comprehensive income (loss)
Accumulated other comprehensive income [Roll Forward]
Beginning balance	(922)	(1,330)	(872)	(1,577)
Other Comprehensive Income (Loss) Net of Tax, Period Change [Abstract]
Ending balance	(957)	(1,322)	(957)	(1,322)
Foreign currency translation [Member]
Accumulated other comprehensive income [Roll Forward]
Beginning balance	(701)	(522)	(629)	(711)
Other Comprehensive Income (Loss) Net of Tax, Period Change [Abstract]
Other comprehensive income (loss), foreign currency translation, net of tax of $(8), $(13), $(18) and $6, respectively	(59)	(20)	(131)	169
Ending balance	(760)	(542)	(760)	(542)
Pension and post retirement [Member]
Accumulated other comprehensive income [Roll Forward]
Beginning balance	(241)	(837)	(259)	(864)
Other Comprehensive Income (Loss) Net of Tax, Period Change [Abstract]
Amortization of deferred actuarial losses into earnings, net of tax of $(5), $(8), $(10) and $(16), respectively	18	27	36	54
Ending balance	(223)	(810)	(223)	(810)
Cash Flow Hedges [Member]
Accumulated other comprehensive income [Roll Forward]
Beginning balance	20	29	16	(2)
Other Comprehensive Income (Loss) Net of Tax, Period Change [Abstract]
Deferral of gains (losses) arising during the period, net of tax of $(5), $(2), $(9) and $(13), respectively	17	9	29	43
Reclassification of realized gains (losses) to sales and cost of sales, net of tax of $4, $3, $6 and $4, respectively	(11)	(8)	(19)	(11)
Ending balance	$ 26	$ 30	$ 26	$ 30