Investments in Marketable Securities - Summary of Investments in Marketable Securities (Details) - USD ($) $ in Millions	Jun. 30, 2021	Mar. 31, 2021
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale debt securities, Amortized cost	$ 1,341	$ 726
Available-for-sale debt securities, Unrealized gains	40	24
Available-for-sale debt securities, Unrealized losses	(9)	(14)
Available-for-sale debt securities, Fair value	1,372	736
Equity investments, Fair value	3,471	4,084
Investments in marketable securities total	4,843	4,820
U.S. government and agency obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale debt securities, Amortized cost	430	217
Available-for-sale debt securities, Unrealized gains	7	4
Available-for-sale debt securities, Unrealized losses	(7)	(10)
Available-for-sale debt securities, Fair value	430	211
Foreign government and agency obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale debt securities, Amortized cost	31
Available-for-sale debt securities, Unrealized gains	0
Available-for-sale debt securities, Unrealized losses	0
Available-for-sale debt securities, Fair value	31
Municipal debt securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale debt securities, Amortized cost	9	8
Available-for-sale debt securities, Unrealized gains	2	2
Available-for-sale debt securities, Unrealized losses	0	0
Available-for-sale debt securities, Fair value	11	10
Commercial paper [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale debt securities, Amortized cost	43	196
Available-for-sale debt securities, Unrealized gains	0	0
Available-for-sale debt securities, Unrealized losses	0	0
Available-for-sale debt securities, Fair value	43	196
Corporate debt securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale debt securities, Amortized cost	641	177
Available-for-sale debt securities, Unrealized gains	23	12
Available-for-sale debt securities, Unrealized losses	(1)	(2)
Available-for-sale debt securities, Fair value	663	187
U.S. government agency mortgage-backed securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale debt securities, Amortized cost	27	31
Available-for-sale debt securities, Unrealized gains	1	1
Available-for-sale debt securities, Unrealized losses	0	0
Available-for-sale debt securities, Fair value	28	32
Non-agency residential mortgage-backed securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale debt securities, Amortized cost	13	1
Available-for-sale debt securities, Unrealized gains	0	0
Available-for-sale debt securities, Unrealized losses	0	0
Available-for-sale debt securities, Fair value	13	1
Non-agency commercial mortgage-backed securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale debt securities, Amortized cost	71	47
Available-for-sale debt securities, Unrealized gains	3	2
Available-for-sale debt securities, Unrealized losses	(1)	(2)
Available-for-sale debt securities, Fair value	73	47
Asset-backed securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale debt securities, Amortized cost	76	49
Available-for-sale debt securities, Unrealized gains	4	3
Available-for-sale debt securities, Unrealized losses	0	0
Available-for-sale debt securities, Fair value	$ 80	$ 52

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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