Amount of loss from the write-down of an asset representing the future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

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Name:	us-gaap_GoodwillImpairmentLoss
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

Goodwill - Narrative (Details) - USD ($) $ in Millions	12 Months Ended
Goodwill - Narrative (Details) - USD ($) $ in Millions	Mar. 31, 2021	Mar. 31, 2020	Mar. 31, 2019
Goodwill [Line Items]
Goodwill impairment losses	$ 0	$ 6,794	$ 0
GBS
Goodwill [Line Items]
Goodwill impairment losses		3,789
GIS
Goodwill [Line Items]
Goodwill impairment losses		$ 3,005