Leases - Narrative (Details) - USD ($) $ in Millions		12 Months Ended
	Apr. 01, 2019	Mar. 31, 2022	Mar. 31, 2021	Mar. 31, 2020	Mar. 31, 2019
Lessee, Lease, Description [Line Items]
Operating lease liability	$ 2,200	$ 1,663	$ 2,257
Operating lease right-of-use assets	2,100	1,548	2,100
Cumulative effect adjustment		(1,792)	175	$ 5,309	$ 8,287
Future lease payments		285
Total lease receivable		$ 298	$ 298
Remaining lease term		7 years	7 years
Opening retained earnings adjustments: adoption of new accounting standards
Lessee, Lease, Description [Line Items]
Cumulative effect adjustment				(13)	11
Impairment charges	89
Minimum
Lessee, Lease, Description [Line Items]
Noncancelable lease terms		5 years
Maximum
Lessee, Lease, Description [Line Items]
Noncancelable lease terms		15 years
Retained Earnings
Lessee, Lease, Description [Line Items]
Cumulative effect adjustment		$ 9,030	$ 8,202	13,022	12,409
Retained Earnings | Opening retained earnings adjustments: adoption of new accounting standards
Lessee, Lease, Description [Line Items]
Cumulative effect adjustment	$ 69			$ (13)	$ 11