Investments in Marketable Securities - Summary of Investments in Marketable Securities (Details) - USD ($) $ in Millions	Dec. 31, 2023	Mar. 31, 2023
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale debt securities, Amortized cost	$ 1,616	$ 1,584
Available-for-sale debt securities, Unrealized gains	7	10
Available-for-sale debt securities, Unrealized losses	(138)	(140)
Available-for-sale debt securities, Fair value	1,485	1,454
Equity investments, Fair value	3,388	3,583
Investments in marketable securities total	4,873	5,037
U.S. government and agency obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale debt securities, Amortized cost	814	796
Available-for-sale debt securities, Unrealized gains	2	7
Available-for-sale debt securities, Unrealized losses	(71)	(59)
Available-for-sale debt securities, Fair value	745	744
Foreign government and agency obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale debt securities, Amortized cost	10	14
Available-for-sale debt securities, Unrealized gains	0	0
Available-for-sale debt securities, Unrealized losses	(1)	(2)
Available-for-sale debt securities, Fair value	9	12
Municipal debt securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale debt securities, Amortized cost	8	8
Available-for-sale debt securities, Unrealized gains	0	1
Available-for-sale debt securities, Unrealized losses	0	(1)
Available-for-sale debt securities, Fair value	8	8
Corporate debt securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale debt securities, Amortized cost	466	487
Available-for-sale debt securities, Unrealized gains	3	2
Available-for-sale debt securities, Unrealized losses	(47)	(59)
Available-for-sale debt securities, Fair value	422	430
U.S. government agency mortgage-backed securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale debt securities, Amortized cost	120	76
Available-for-sale debt securities, Unrealized gains	1	0
Available-for-sale debt securities, Unrealized losses	(3)	(3)
Available-for-sale debt securities, Fair value	118	73
Non-agency residential mortgage-backed securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale debt securities, Amortized cost	9	10
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	8	9
Non-agency commercial mortgage-backed securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale debt securities, Amortized cost	65	66
Available-for-sale debt securities, Unrealized gains	0	0
Available-for-sale debt securities, Unrealized losses	(9)	(8)
Available-for-sale debt securities, Fair value	56	58
Asset-backed securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale debt securities, Amortized cost	124	127
Available-for-sale debt securities, Unrealized gains	1	0
Available-for-sale debt securities, Unrealized losses	(6)	(7)
Available-for-sale debt securities, Fair value	$ 119	$ 120

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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