Income Taxes - Gross Unrecognized Tax Benefits (Details) - USD ($) $ in Millions	12 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Mar. 31, 2022
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Unrecognized tax benefits at beginning of period	$ 1,399	$ 1,523	$ 1,754
Additions based on tax positions related to prior years	10	0	14
Reductions based on tax positions related to prior years	(2)	(26)	(131)
Additions based on tax positions related to current year	64	21	14
Reductions based on settlements	(8)	(96)	(20)
Reductions based on the lapse of the applicable statutes of limitations	(2)	(16)	(102)
Exchange rate fluctuations	2	(7)	(6)
Unrecognized tax benefits at end of period	$ 1,463	$ 1,399	$ 1,523