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Business Acquisitions and Divestitures - Acquisitions (Details) - USD ($) $ in Millions			12 Months Ended
	Nov. 01, 2022	Oct. 31, 2022	Mar. 31, 2024	Mar. 31, 2023	Mar. 31, 2022
Discontinued Operations Disclosures
Goodwill			$ 10,132	$ 9,947	$ 9,451
U.S. Pharmaceutical
Discontinued Operations Disclosures
Goodwill			4,123	4,050	$ 3,923
Rx Savings Solutions, LLC
Discontinued Operations Disclosures
Fair value adjustment gain			78
Rx Savings Solutions, LLC \| RxTs Segment
Discontinued Operations Disclosures
Business acquisition, percentage of controlling interest in combined business	100.00%
Cash payment to acquire business	$ 600
Contingent consideration	92
Other current liabilities			14	$ 83
Other non-current liabilities			$ 9
Acquired identifiable intangible assets	$ 229
Weighted average life of intangibles	12 years
Goodwill	$ 463
Rx Savings Solutions, LLC \| RxTs Segment \| Maximum
Discontinued Operations Disclosures
Contingent consideration	$ 275
SCRI Oncology, LLC \| U.S. Pharmaceutical
Discontinued Operations Disclosures
Business acquisition, percentage of controlling interest in combined business		51.00%
Cash payment to acquire business		$ 166
Acquired identifiable intangible assets		$ 177
Weighted average life of intangibles		17 years
Goodwill		$ 113
Goodwill, expected tax deductible amount		46
Noncontrolling interest		225
SCRI Oncology, LLC \| U.S. Pharmaceutical \| SCRI
Discontinued Operations Disclosures
Noncontrolling interest		202
SCRI Oncology, LLC \| U.S. Pharmaceutical \| USOR
Discontinued Operations Disclosures
Noncontrolling interest		$ 23