Investments in Marketable Securities - Summary of Investments in Marketable Securities (Details) - USD ($) $ in Millions	Sep. 30, 2022	Mar. 31, 2022
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale debt securities, Amortized cost	$ 1,404	$ 1,372
Available-for-sale debt securities, Unrealized gains	3	6
Available-for-sale debt securities, Unrealized losses	(190)	(74)
Available-for-sale debt securities, Fair value	1,217	1,304
Equity investments, Fair value	3,171	3,649
Investments in marketable securities total	4,388	4,953
U.S. government and agency obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale debt securities, Amortized cost	642	538
Available-for-sale debt securities, Unrealized gains	0	0
Available-for-sale debt securities, Unrealized losses	(78)	(29)
Available-for-sale debt securities, Fair value	564	509
Foreign government and agency obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale debt securities, Amortized cost	17	26
Available-for-sale debt securities, Unrealized gains	0	0
Available-for-sale debt securities, Unrealized losses	(5)	(3)
Available-for-sale debt securities, Fair value	12	23
Municipal debt securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale debt securities, Amortized cost	9	9
Available-for-sale debt securities, Unrealized gains	1	1
Available-for-sale debt securities, Unrealized losses	(1)	0
Available-for-sale debt securities, Fair value	9	10
Corporate debt securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale debt securities, Amortized cost	513	598
Available-for-sale debt securities, Unrealized gains	1	4
Available-for-sale debt securities, Unrealized losses	(85)	(34)
Available-for-sale debt securities, Fair value	429	568
U.S. government agency mortgage-backed securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale debt securities, Amortized cost	51	20
Available-for-sale debt securities, Unrealized gains	0	0
Available-for-sale debt securities, Unrealized losses	(4)	0
Available-for-sale debt securities, Fair value	47	20
Non-agency residential mortgage-backed securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale debt securities, Amortized cost	10	11
Available-for-sale debt securities, Unrealized gains	0	0
Available-for-sale debt securities, Unrealized losses	(1)	(1)
Available-for-sale debt securities, Fair value	9	10
Non-agency commercial mortgage-backed securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale debt securities, Amortized cost	87	88
Available-for-sale debt securities, Unrealized gains	1	1
Available-for-sale debt securities, Unrealized losses	(8)	(3)
Available-for-sale debt securities, Fair value	80	86
Asset-backed securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale debt securities, Amortized cost	75	82
Available-for-sale debt securities, Unrealized gains	0	0
Available-for-sale debt securities, Unrealized losses	(8)	(4)
Available-for-sale debt securities, Fair value	$ 67	$ 78

Amount, before tax, of unrealized gain in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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