Investments in Marketable Securities - Summary of Contractual Maturities of Available-for-Sale Debt Securities (Details) - USD ($) $ in Millions		Sep. 30, 2022	Mar. 31, 2022
Available-for-sale debt securities, Amortized cost
Due within 1 Year, Amortized cost		$ 77
Due after 1 Year through 5 Years, Amortized cost		351
Due after 5 Years through 10 Years, Amortized cost		358
Due after 10 Years, Amortized cost		395
Mortgage-backed and asset-backed securities, Amortized cost	[1]	223
Available-for-sale debt securities, Amortized cost		$ 1,404	$ 1,372
Debt Securities, Available-for-sale, Maturity Allocation [Extensible List]		us-gaap:DebtSecuritiesMaturityAllocationContractualMaturityMember
Available-for-sale debt securities, Fair value
Due within 1 Year, Fair value		$ 76
Due after 1 Year through 5 Years, Fair value		326
Due after 5 Years through 10 Years, Fair value		308
Due after 10 Years, Fair value		304
Mortgage-backed and asset-backed securities, Fair value	[1]	203
Total, Fair value		$ 1,217	$ 1,304
Debt Securities, Available-for-sale, Maturity Allocation [Extensible List]		us-gaap:DebtSecuritiesMaturityAllocationContractualMaturityMember

[1] Mortgage-backed and asset-backed securities are shown separately from other maturity groupings as these securities have multiple maturity dates.