Equity - Accumulated Other Comprehensive Income (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Mar. 31, 2023	Mar. 31, 2022	Mar. 31, 2023	Mar. 31, 2022
Increase (Decrease) in Accumulated Other Comprehensive Income [Roll Forward]
Beginning Balance			$ 17,402
Other comprehensive income	$ 30	$ (7)	102	$ 85
Ending Balance	17,078	17,688	17,078	17,688
AOCI Attributable to Parent
Increase (Decrease) in Accumulated Other Comprehensive Income [Roll Forward]
Beginning Balance	(864)	(347)	(911)	(434)
Ending Balance	(846)	(345)	(846)	(345)
Foreign currency translation adjustments
Increase (Decrease) in Accumulated Other Comprehensive Income [Roll Forward]
Beginning Balance	(842)	(337)	(901)	(421)
Other comprehensive income	(1)	(6)	58	78
Other comprehensive income, tax effect	0	0	0	0
Ending Balance	(843)	(343)	(843)	(343)
Realized and unrealized gains (losses) on derivatives
Increase (Decrease) in Accumulated Other Comprehensive Income [Roll Forward]
Beginning Balance	(22)	(13)	(11)	(17)
Other comprehensive income, before reclassifications	13	12	4	16
Reclassification to income	6	(3)	4	(3)
Other comprehensive income, tax effect	3	3	1	6
Reclassification to income, tax effect	1	(2)	0	(2)
Ending Balance	(3)	(4)	(3)	(4)
Pension and postretirement plans
Increase (Decrease) in Accumulated Other Comprehensive Income [Roll Forward]
Beginning Balance	0	3	1	4
Reclassification to income	0	(1)	(1)	(2)
Reclassification to income, tax effect	(1)	(1)	(1)	(1)
Ending Balance	$ 0	$ 2	$ 0	$ 2