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, 2022	Mar. 31, 2021	Mar. 31, 2020
Available-for-sale debt securities:
Unrealized losses on securities for which the fair value option was elected	$ (41)
Realized (losses) gains on sales	(4)	$ 20	$ 9
Other-than-temporary impairment	0		(8)
Equity investments:
Unrealized (losses) gains	(158)	114	41
Realized gains on sales	$ 22	$ 15	$ 5