Revenue - Change in Contract Liabilities (Details) - USD ($) $ in Millions	12 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Change In Contract With Customer, Liability [Roll Forward]
Balance, beginning of period	$ 1,756	$ 1,886
Deferred revenue	2,933	2,910
Recognition of deferred revenue	(2,922)	(2,925)
Currency translation adjustment	128	(48)
Other	(194)	(67)
Balance, end of period	1,701	$ 1,756
HHS Business
Change In Contract With Customer, Liability [Roll Forward]
Other	52
HPS Business
Change In Contract With Customer, Liability [Roll Forward]
Other	$ 62