Restructuring Costs - Schedule of Restructuring Reserve by Type of Cost (Details) - USD ($) $ in Millions	3 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Restructuring Reserve [Roll Forward]
Restructuring reserve, beginning balance	$ 87
Expense	83	$ 10
Utilized/Paid	59
Restructuring reserve, ending balance	111
Severance and benefits
Restructuring Reserve [Roll Forward]
Restructuring reserve, beginning balance	85
Expense	79
Utilized/Paid	56
Restructuring reserve, ending balance	108
Other
Restructuring Reserve [Roll Forward]
Restructuring reserve, beginning balance	2
Expense	4
Utilized/Paid	3
Restructuring reserve, ending balance	$ 3