Restructuring Costs (Details) - USD ($) $ in Millions	12 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Mar. 31, 2019
Restructuring Cost and Reserve [Line Items]
Restructuring costs	$ 551	$ 252	$ 465
Restructuring Reserve [Abstract]
Accrued expenses and other current liabilities	225	145
Other long-term liabilities	45	35
Total	270	180
Fiscal 2019 Plan
Restructuring Cost and Reserve [Line Items]
Restructuring costs	(3)	(25)
Restructuring Reserve [Abstract]
Total	13	30	206
Restructuring cost incurred to date	296
Fiscal 2018 Plan
Restructuring Cost and Reserve [Line Items]
Restructuring costs		(11)
Restructuring Reserve [Abstract]
Total		20	94
Restructuring cost incurred to date	479
Fiscal 2018 Plan
Restructuring Reserve [Abstract]
Restructuring cost incurred to date	998
Workforce Reductions | Fiscal 2019 Plan
Restructuring Cost and Reserve [Line Items]
Restructuring costs	(1)	(25)
Restructuring Reserve [Abstract]
Total	7	25	138
Restructuring cost incurred to date	279
Workforce Reductions | Fiscal 2018 Plan
Restructuring Cost and Reserve [Line Items]
Restructuring costs		(10)
Restructuring Reserve [Abstract]
Total		20	59
Restructuring cost incurred to date	337
Workforce Reductions | Fiscal 2018 Plan
Restructuring Reserve [Abstract]
Restructuring cost incurred to date	802
Facilities Costs | Fiscal 2019 Plan
Restructuring Cost and Reserve [Line Items]
Restructuring costs	(2)	0
Restructuring Reserve [Abstract]
Total	6	5	68
Restructuring cost incurred to date	17
Facilities Costs | Fiscal 2018 Plan
Restructuring Cost and Reserve [Line Items]
Restructuring costs		(1)
Restructuring Reserve [Abstract]
Total		$ 0	$ 35
Restructuring cost incurred to date	142
Facilities Costs | Fiscal 2018 Plan
Restructuring Reserve [Abstract]
Restructuring cost incurred to date	$ 196