Business Restructuring Charges - Changes in Restructuring Balance (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2022
Restructuring Cost and Reserve [Line Items]
Restructuring Charges, Statement of Income or Comprehensive Income [Extensible Enumeration]	Integration, restructuring and transaction expense	Integration, restructuring and transaction expense	Integration, restructuring and transaction expense
Restructuring Reserve [Roll Forward]
Beginning balance	$ 80	$ 35	$ 19
Charged to expense	387	239	123
Cash payments	(305)	(165)	(82)
Non-cash settlements	(104)	(30)	(25)
Other adjustments	2	1	1
Ending balance	60	80	35
Employee Termination
Restructuring Reserve [Roll Forward]
Beginning balance	79	24	14
Charged to expense	80	117	21
Cash payments	(103)	(62)	(11)
Non-cash settlements	0	0	0
Other adjustments	2	0	0
Ending balance	58	79	24
Other
Restructuring Reserve [Roll Forward]
Beginning balance	1	11	5
Charged to expense	307	122	103
Cash payments	(202)	(103)	(71)
Non-cash settlements	(104)	(30)	(25)
Other adjustments	0	1	1
Ending balance	$ 2	$ 1	$ 11