Cash and Cash Equivalents and Investments in Marketable Securities - Schedule of Gains and Losses on Investments in Marketable Securities Presented in Our Consolidated Statement of Income (Details) - USD ($) $ in Millions		12 Months Ended
		Mar. 31, 2024	Mar. 31, 2023	Mar. 31, 2022
Available-for-sale debt securities:
Unrealized losses on securities for which the fair value option was elected	[1]	$ (13)	$ (17)	$ (41)
Realized (losses) gains on sales		(1)	(38)	(4)
Equity investments:
Unrealized gains (losses)		296	(297)	(158)
Realized (losses) gains on sales		$ (137)	$ (23)	$ 22

[1] Starting in fiscal 2022, we elected the fair value option for certain debt securities.