Business Acquisitions and Divestitures - Identified Assets Acquired and Liabilities Assumed (Oncology Research) (Details) - USD ($) $ in Millions	Oct. 31, 2022	Mar. 31, 2023	Mar. 31, 2022	Mar. 31, 2021
Identifiable assets acquired and liabilities assumed:
Goodwill		$ 9,947	$ 9,451	$ 9,493
U.S. Pharmaceutical
Identifiable assets acquired and liabilities assumed:
Goodwill		$ 4,050	$ 3,923	$ 3,963
SCRI Oncology, LLC | U.S. Pharmaceutical
Purchase consideration:
Cash	$ 173
Contribution of USOR	40
Total purchase consideration	213
Identifiable assets acquired and liabilities assumed:
Receivables	224
Property, plant, and equipment	22
Operating lease right-of-use assets	31
Intangible assets	177
Current liabilities	(42)
Long-term operating lease liabilities	(29)
Other non-current liabilities	(43)
Total identifiable net assets	340
Noncontrolling interest	(225)
Additional paid-in capital	(22)
Goodwill	120
Net assets acquired	$ 213