Restructuring and Impairment Costs - Schedule of Restructuring Reserve (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Mar. 31, 2024	Mar. 31, 2023
Restructuring Reserve [Roll Forward]
Restructuring reserve	$ 64	$ 53	$ 64	$ 53
Restructuring reserve	105	0	105	0
2024 Restructuring Plan
Restructuring Reserve [Roll Forward]
Restructuring reserve beginning balance	54		51
Plan charges	127		138
Utilized - cash	(8)		(17)
Noncash and other adjustments	(4)		(3)
Restructuring reserve ending balance	169		169
2023 Restructuring Plan
Restructuring Reserve [Roll Forward]
Restructuring reserve beginning balance		45		60
Plan charges		17		24
Utilized - cash		(10)		(37)
Noncash and other adjustments		1		6
Restructuring reserve ending balance		53		53
Employee Severance and Termination Benefits | 2024 Restructuring Plan
Restructuring Reserve [Roll Forward]
Restructuring reserve beginning balance	58		56
Plan charges	127		138
Utilized - cash	(8)		(17)
Noncash and other adjustments	(2)		(2)
Restructuring reserve ending balance	175		175
Employee Severance and Termination Benefits | 2023 Restructuring Plan
Restructuring Reserve [Roll Forward]
Restructuring reserve beginning balance		49		69
Plan charges		17		24
Utilized - cash		(10)		(37)
Noncash and other adjustments		1		1
Restructuring reserve ending balance		57		57
Currency Translation | 2024 Restructuring Plan
Restructuring Reserve [Roll Forward]
Restructuring reserve beginning balance	(4)		(5)
Plan charges	0		0
Utilized - cash	0		0
Noncash and other adjustments	(2)		(1)
Restructuring reserve ending balance	$ (6)		$ (6)
Currency Translation | 2023 Restructuring Plan
Restructuring Reserve [Roll Forward]
Restructuring reserve beginning balance		(4)		(9)
Plan charges		0		0
Utilized - cash		0		0
Noncash and other adjustments		0		5
Restructuring reserve ending balance		$ (4)		$ (4)