Cash and Cash Equivalents and Investments in Marketable Securities - Summary of Investments in Marketable Securities (Details) - USD ($) $ in Millions	Mar. 31, 2021	Mar. 31, 2020
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale debt securities, Amortized cost	$ 726	$ 1,381
Available-for-sale debt securities, Unrealized gains	24	30
Available-for-sale debt securities, Unrealized losses	(14)	(10)
Available-for-sale debt securities, Fair value	736	1,401
Equity investments, Fair value	4,084	2,419
Investments in marketable securities total	4,820	3,820
U.S. government and agency obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale debt securities, Amortized cost	217	160
Available-for-sale debt securities, Unrealized gains	4	16
Available-for-sale debt securities, Unrealized losses	(10)	0
Available-for-sale debt securities, Fair value	211	176
Municipal debt securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale debt securities, Amortized cost	8	9
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	10	11
Commercial paper [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale debt securities, Amortized cost	196	604
Available-for-sale debt securities, Unrealized gains	0	0
Available-for-sale debt securities, Unrealized losses	0	(3)
Available-for-sale debt securities, Fair value	196	601
Corporate debt securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale debt securities, Amortized cost	177	188
Available-for-sale debt securities, Unrealized gains	12	10
Available-for-sale debt securities, Unrealized losses	(2)	(1)
Available-for-sale debt securities, Fair value	187	197
U.S. government agency mortgage-backed securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale debt securities, Amortized cost	31	47
Available-for-sale debt securities, Unrealized gains	1	2
Available-for-sale debt securities, Unrealized losses	0	0
Available-for-sale debt securities, Fair value	32	49
Non-agency residential mortgage-backed securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale debt securities, Amortized cost	1	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	1	1
Non-agency commercial mortgage-backed securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale debt securities, Amortized cost	47	47
Available-for-sale debt securities, Unrealized gains	2	0
Available-for-sale debt securities, Unrealized losses	(2)	(2)
Available-for-sale debt securities, Fair value	47	45
Asset-backed securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale debt securities, Amortized cost	49	75
Available-for-sale debt securities, Unrealized gains	3	0
Available-for-sale debt securities, Unrealized losses	0	(3)
Available-for-sale debt securities, Fair value	$ 52	72
Certificates of deposit [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale debt securities, Amortized cost		250
Available-for-sale debt securities, Unrealized gains		0
Available-for-sale debt securities, Unrealized losses		(1)
Available-for-sale debt securities, Fair value		$ 249

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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