Investments in Marketable Securities - Summary of Investments in Marketable Securities (Details) - USD ($) $ in Millions	Jun. 30, 2024	Mar. 31, 2024
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale debt securities, Amortized cost	$ 1,614	$ 1,622
Available-for-sale debt securities, Unrealized gains	4	4
Available-for-sale debt securities, Unrealized losses	(165)	(158)
Available-for-sale debt securities, Fair value	1,453	1,468
Equity investments, Fair value	3,088	3,037
Investments in marketable securities total	4,541	4,505
U.S. government and agency obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale debt securities, Amortized cost	811	783
Available-for-sale debt securities, Unrealized gains	1	1
Available-for-sale debt securities, Unrealized losses	(96)	(87)
Available-for-sale debt securities, Fair value	716	697
Foreign government and agency obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale debt securities, Amortized cost	16	13
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	15	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	0
Available-for-sale debt securities, Unrealized losses	0	(1)
Available-for-sale debt securities, Fair value	8	7
Corporate debt securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale debt securities, Amortized cost	463	477
Available-for-sale debt securities, Unrealized gains	2	2
Available-for-sale debt securities, Unrealized losses	(50)	(49)
Available-for-sale debt securities, Fair value	415	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	123
Available-for-sale debt securities, Unrealized gains	0	0
Available-for-sale debt securities, Unrealized losses	(6)	(5)
Available-for-sale debt securities, Fair value	114	118
Non-agency residential mortgage-backed securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale debt securities, Amortized cost	12	12
Available-for-sale debt securities, Unrealized gains	0	0
Available-for-sale debt securities, Unrealized losses	(2)	(1)
Available-for-sale debt securities, Fair value	10	11
Non-agency commercial mortgage-backed securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale debt securities, Amortized cost	57	64
Available-for-sale debt securities, Unrealized gains	0	0
Available-for-sale debt securities, Unrealized losses	(6)	(9)
Available-for-sale debt securities, Fair value	51	55
Asset-backed securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale debt securities, Amortized cost	127	142
Available-for-sale debt securities, Unrealized gains	1	1
Available-for-sale debt securities, Unrealized losses	(4)	(5)
Available-for-sale debt securities, Fair value	$ 124	$ 138

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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Amount, before tax, of unrealized loss 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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