Restructuring Costs - Narrative (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Restructuring Cost and Reserve [Line Items]
Restructuring costs	$ 145	$ 265	$ 212	$ 337
Fiscal 2022 Plan
Restructuring Cost and Reserve [Line Items]
Restructuring costs			213
Amortization of right-of-use assets and interest expense for leases vacated			7
Fiscal 2022 Plan | Employee Severance
Restructuring Cost and Reserve [Line Items]
Restructuring costs			163
Fiscal 2022 Plan | Facilities Costs
Restructuring Cost and Reserve [Line Items]
Restructuring costs			50
Fiscal 2021 Plan
Restructuring Cost and Reserve [Line Items]
Restructuring costs			2
Cost incurred to date	540		540
Fiscal 2021 Plan | Employee Severance
Restructuring Cost and Reserve [Line Items]
Restructuring costs			(3)
Cost incurred to date	498		498
Fiscal 2021 Plan | Facilities Costs
Restructuring Cost and Reserve [Line Items]
Restructuring costs			5
Cost incurred to date	42		42
Fiscal 2020 Plan
Restructuring Cost and Reserve [Line Items]
Restructuring costs			(2)
Cost incurred to date	294		294
Fiscal 2020 Plan | Employee Severance
Restructuring Cost and Reserve [Line Items]
Restructuring costs			(2)
Cost incurred to date	277		277
Fiscal 2020 Plan | Facilities Costs
Restructuring Cost and Reserve [Line Items]
Restructuring costs			0
Cost incurred to date	17		17
Other Prior Year Plans
Restructuring Cost and Reserve [Line Items]
Cost incurred to date	1,478		1,478
Other Prior Year Plans | Employee Severance
Restructuring Cost and Reserve [Line Items]
Cost incurred to date	1,140		1,140
Other Prior Year Plans | Facilities Costs
Restructuring Cost and Reserve [Line Items]
Cost incurred to date	$ 338		$ 338