Share-Based Compensation - Schedule of Data Related to Stock Option Activity (Details) - Options to purchase common stock - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
Mar. 31, 2021	Mar. 31, 2020	Mar. 31, 2019
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted-average grant date fair value per stock option (in dollars per share)	$ 0	$ 0	$ 34.98
Aggregate intrinsic value on exercise	$ 5	$ 17	$ 16
Cash received upon exercise	38	66	29
Tax benefits realized related to exercise	4	4	4
Total fair value of stock options vested	10	16	16
Total compensation cost, net of estimated forfeitures, related to unvested stock options not yet recognized, pre-tax	$ 2	$ 6	$ 15
Weighted-average period in years over which stock option compensation cost is expected to be recognized	2 years	2 years	2 years

Amount of cost not yet recognized for nonvested award under share-based payment arrangement.

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
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Weighted-average period over which cost not yet recognized is expected to be recognized for award under share-based payment arrangement, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

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Amount of tax benefit from exercise of option under share-based payment arrangement.

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Amount of cash inflow from exercise of option under share-based payment arrangement.

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Amount of accumulated difference between fair value of underlying shares on dates of exercise and exercise price on options exercised (or share units converted) into shares.

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The weighted average grant-date fair value of options granted during the reporting period as calculated by applying the disclosed option pricing methodology.

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Fair value of options vested. Excludes equity instruments other than options, for example, but not limited to, share units, stock appreciation rights, restricted stock.

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