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Investments in Marketable Securities - Summary of Investments in Marketable Securities (Details) - USD ($)
$ in Millions
Jun. 30, 2023
Mar. 31, 2023
Schedule of Available-for-sale Securities [Line Items]    
Available-for-sale debt securities, Amortized cost $ 1,586 $ 1,584
Available-for-sale debt securities, Unrealized gains 3 10
Available-for-sale debt securities, Unrealized losses (156) (140)
Available-for-sale debt securities, Fair value 1,433 1,454
Equity investments, Fair value 3,626 3,583
Investments in marketable securities total 5,059 5,037
U.S. government and agency obligations [Member]    
Schedule of Available-for-sale Securities [Line Items]    
Available-for-sale debt securities, Amortized cost 783 796
Available-for-sale debt securities, Unrealized gains 1 7
Available-for-sale debt securities, Unrealized losses (70) (59)
Available-for-sale debt securities, Fair value 714 744
Foreign government and agency obligations [Member]    
Schedule of Available-for-sale Securities [Line Items]    
Available-for-sale debt securities, Amortized cost 15 14
Available-for-sale debt securities, Unrealized gains 0 0
Available-for-sale debt securities, Unrealized losses (2) (2)
Available-for-sale debt securities, Fair value 13 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 1 1
Available-for-sale debt securities, Unrealized losses (1) (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 480 487
Available-for-sale debt securities, Unrealized gains 1 2
Available-for-sale debt securities, Unrealized losses (60) (59)
Available-for-sale debt securities, Fair value 421 430
U.S. government agency mortgage-backed securities [Member]    
Schedule of Available-for-sale Securities [Line Items]    
Available-for-sale debt securities, Amortized cost 95 76
Available-for-sale debt securities, Unrealized gains 0 0
Available-for-sale debt securities, Unrealized losses (4) (3)
Available-for-sale debt securities, Fair value 91 73
Non-agency residential mortgage-backed securities [Member]    
Schedule of Available-for-sale Securities [Line Items]    
Available-for-sale debt securities, Amortized cost 10 10
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 8 9
Non-agency commercial mortgage-backed securities [Member]    
Schedule of Available-for-sale Securities [Line Items]    
Available-for-sale debt securities, Amortized cost 66 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 57 58
Asset-backed securities [Member]    
Schedule of Available-for-sale Securities [Line Items]    
Available-for-sale debt securities, Amortized cost 129 127
Available-for-sale debt securities, Unrealized gains 0 0
Available-for-sale debt securities, Unrealized losses (8) (7)
Available-for-sale debt securities, Fair value $ 121 $ 120