Cash and Cash Equivalents and Investments in Marketable Securities - Schedule of Continuous Unrealized Losses on Available-For-Sale Debt Securities (Details) - USD ($) $ in Millions	Mar. 31, 2025	Mar. 31, 2024
Debt Securities, Available-for-Sale [Line Items]
Available-for-sale debt securities, Less than 12 months, Fair value	$ 262	$ 419
Available-for-sale debt securities, 12 months or longer, Fair value	956	852
Available-for-sale debt securities, Total, Fair value	1,218	1,271
Available-for-sale debt securities, Less than 12 months, Unrealized losses	(3)	(17)
Available-for-sale debt securities, 12 months or longer, Unrealized losses	(136)	(141)
Available-for-sale debt securities, Total, Unrealized losses	(139)	(158)
U.S. government and agency obligations [Member]
Debt Securities, Available-for-Sale [Line Items]
Available-for-sale debt securities, Less than 12 months, Fair value	104	317
Available-for-sale debt securities, 12 months or longer, Fair value	534	336
Available-for-sale debt securities, Total, Fair value	638	653
Available-for-sale debt securities, Less than 12 months, Unrealized losses	(1)	(13)
Available-for-sale debt securities, 12 months or longer, Unrealized losses	(82)	(74)
Available-for-sale debt securities, Total, Unrealized losses	(83)	(87)
Foreign government and agency obligations [Member]
Debt Securities, Available-for-Sale [Line Items]
Available-for-sale debt securities, Less than 12 months, Fair value	7	1
Available-for-sale debt securities, 12 months or longer, Fair value	6	8
Available-for-sale debt securities, Total, Fair value	13	9
Available-for-sale debt securities, Less than 12 months, Unrealized losses	0	0
Available-for-sale debt securities, 12 months or longer, Unrealized losses	(1)	(1)
Available-for-sale debt securities, Total, Unrealized losses	(1)	(1)
Municipal debt securities [Member]
Debt Securities, Available-for-Sale [Line Items]
Available-for-sale debt securities, Less than 12 months, Fair value	0	0
Available-for-sale debt securities, 12 months or longer, Fair value	2	2
Available-for-sale debt securities, Total, Fair value	2	2
Available-for-sale debt securities, Less than 12 months, Unrealized losses	0	0
Available-for-sale debt securities, 12 months or longer, Unrealized losses	(1)	(1)
Available-for-sale debt securities, Total, Unrealized losses	(1)	(1)
Corporate debt securities [Member]
Debt Securities, Available-for-Sale [Line Items]
Available-for-sale debt securities, Less than 12 months, Fair value	42	31
Available-for-sale debt securities, 12 months or longer, Fair value	288	339
Available-for-sale debt securities, Total, Fair value	330	370
Available-for-sale debt securities, Less than 12 months, Unrealized losses	(1)	(3)
Available-for-sale debt securities, 12 months or longer, Unrealized losses	(39)	(46)
Available-for-sale debt securities, Total, Unrealized losses	(40)	(49)
U.S. government agency mortgage-backed securities [Member]
Debt Securities, Available-for-Sale [Line Items]
Available-for-sale debt securities, Less than 12 months, Fair value	68	51
Available-for-sale debt securities, 12 months or longer, Fair value	37	49
Available-for-sale debt securities, Total, Fair value	105	100
Available-for-sale debt securities, Less than 12 months, Unrealized losses	(1)	(1)
Available-for-sale debt securities, 12 months or longer, Unrealized losses	(4)	(4)
Available-for-sale debt securities, Total, Unrealized losses	(5)	(5)
Non-agency residential mortgage-backed securities [Member]
Debt Securities, Available-for-Sale [Line Items]
Available-for-sale debt securities, Less than 12 months, Fair value	1	1
Available-for-sale debt securities, 12 months or longer, Fair value	7	7
Available-for-sale debt securities, Total, Fair value	8	8
Available-for-sale debt securities, Less than 12 months, Unrealized losses	0	0
Available-for-sale debt securities, 12 months or longer, Unrealized losses	(1)	(1)
Available-for-sale debt securities, Total, Unrealized losses	(1)	(1)
Non-agency commercial mortgage-backed securities [Member]
Debt Securities, Available-for-Sale [Line Items]
Available-for-sale debt securities, Less than 12 months, Fair value	3	1
Available-for-sale debt securities, 12 months or longer, Fair value	41	53
Available-for-sale debt securities, Total, Fair value	44	54
Available-for-sale debt securities, Less than 12 months, Unrealized losses	0	0
Available-for-sale debt securities, 12 months or longer, Unrealized losses	(5)	(9)
Available-for-sale debt securities, Total, Unrealized losses	(5)	(9)
Asset-backed securities [Member]
Debt Securities, Available-for-Sale [Line Items]
Available-for-sale debt securities, Less than 12 months, Fair value	37	17
Available-for-sale debt securities, 12 months or longer, Fair value	41	58
Available-for-sale debt securities, Total, Fair value	78	75
Available-for-sale debt securities, Less than 12 months, Unrealized losses	0	0
Available-for-sale debt securities, 12 months or longer, Unrealized losses	(3)	(5)
Available-for-sale debt securities, Total, Unrealized losses	$ (3)	$ (5)

Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in continuous unrealized loss position for more than 12 months, without allowance for credit loss. Includes beneficial interest in securitized financial asset.

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