Commitments and Contingent Liabilities - Litigation and Claims Involving Distribution of Controlled Substances (Details) $ in Millions				3 Months Ended		6 Months Ended		12 Months Ended
	Aug. 08, 2025 USD ($)	Jun. 12, 2025 USD ($)	Nov. 12, 2024 USD ($)	Sep. 30, 2025 USD ($) case distributor state jurisdiction	Sep. 30, 2024 USD ($)	Sep. 30, 2025 USD ($) case distributor state jurisdiction	Sep. 30, 2024 USD ($)	Mar. 31, 2025 USD ($)	Mar. 31, 2024 USD ($)	Feb. 12, 2025 USD ($)	Nov. 27, 2024 USD ($)
Loss Contingencies [Line Items]
Claims and litigation charges				$ 2	$ 4	$ 2	$ (108)
National Prescription Opioid Litigation
Loss Contingencies [Line Items]
Loss contingency, claims settled, number of jurisdictions not participating in settlement | jurisdiction				1		1
National Prescription Opioid Litigation | Canada
Loss Contingencies [Line Items]
Complaints filed against the entity | case				4		4
An individual | National Prescription Opioid Litigation | Canada
Loss Contingencies [Line Items]
Complaints filed against the entity | case				1		1
National Prescription Opioid Litigation
Loss Contingencies [Line Items]
Number of other national distributors named in suit | distributor				2		2
Number of states in which court cases are pending | state				48		48
Loss contingency, number of cases dismissed | case				2,300		2,300
Portion of settlement award to be used by state and local government for remediation (as a percent)				85.00%		85.00%
Amounts awarded to plaintiff	$ 72	$ 37	$ 192
Claims and litigation charges								$ 114	$ 149
Restricted cash in escrow										$ 114	$ 149
National Prescription Opioid Litigation | Acute Care Hospital Settlement
Loss Contingencies [Line Items]
Settlement payment						$ 146
National Prescription Opioid Litigation | Third-Party Payor Settlement
Loss Contingencies [Line Items]
Settlement payment						14
National Prescription Opioid Litigation | North American Pharmaceutical Segment and Corporate Expenses
Loss Contingencies [Line Items]
Claims and litigation charges								$ 57
National Prescription Opioid Litigation | State of Alabama and Subdivisions
Loss Contingencies [Line Items]
Settlement payment						89
Award payable under proposed framework						$ 85
National Prescription Opioid Litigation | Native American Tribes Other Than Cherokee Nation
Loss Contingencies [Line Items]
Litigation settlement, amount awarded to other party, percentage of total settlement to be used to remediate damages (as a percent)				0.85		0.85
National Prescription Opioid Litigation | Settling Governmental Entities and Cherokee Nation | Settled Litigation
Loss Contingencies [Line Items]
Settlement payment						$ 497
National Prescription Opioid Litigation | Three Largest U.S. Pharmaceutical Distributors
Loss Contingencies [Line Items]
Settlement payment						2,500
Award payable under proposed framework						5,400
National Prescription Opioid Litigation | Three National Pharmaceutical Distributors | State of West Virginia and Subdivisions
Loss Contingencies [Line Items]
Settlement payment						68
National Prescription Opioid Litigation | Three National Pharmaceutical Distributors | State of West Virginia and Subdivisions | Settled Litigation
Loss Contingencies [Line Items]
Award payable under proposed framework						84
National Prescription Opioid Litigation | Three National Pharmaceutical Distributors | Cherokee Nation
Loss Contingencies [Line Items]
Settlement payment						140
Award payable under proposed framework						$ 56