Goodwill and Intangible Assets, Net - Goodwill Narrative (Details) $ in Millions	3 Months Ended	12 Months Ended
Sep. 30, 2020 segment	Mar. 31, 2023 USD ($) segment	Mar. 31, 2022 USD ($)	Mar. 31, 2021 USD ($)
Goodwill [Line Items]
Number of reportable segments \| segment	4	4
Goodwill impairment charge		$ 0	$ 0	$ 69
Retail Pharmacy Reporting Unit \| International
Goodwill [Line Items]
Goodwill impairment charge			$ 700	$ 69

Amount of loss from the write-down of an asset representing the future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

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