Aggregate number of common shares reserved for future issuance.

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

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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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The difference between the maximum number of shares (or other type of equity) authorized for issuance under the plan (including the effects of amendments and adjustments), and the sum of: 1) the number of shares (or other type of equity) already issued upon exercise of options or other equity-based awards under the plan; and 2) shares (or other type of equity) reserved for issuance on granting of outstanding awards, net of cancellations and forfeitures, if applicable.

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Purchase price of common stock expressed as a percentage of its fair value.

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Number of shares issued during the period as a result of an employee stock purchase plan.

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Aggregate change in value for stock issued during the period as a result of employee stock purchase plan.

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Share-Based Compensation - Employee Stock Purchase Plan (Details) - USD ($) $ in Millions	12 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Mar. 31, 2019	May 29, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unvested share-based payment awards	$ 300.1			$ 121.5
Nonvested awards, total compensation cost not yet recognized, period for recognition	1 year 10 months 2 days
Employee Stock Purchase Plans
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share based compensation arrangement by share based payment award, market price offering date percentage	85.00%
Common stock, capital shares reserved for future issuance (in shares)	17,222,291
Number of shares available for grant (in shares)	5,929,687
Stock issued during period, shares, employee stock purchase plans (in shares)	712,220	787,284	549,796
Stock issued during period, value, employee stock purchase plan	$ 57.7	$ 55.6	$ 39.6
Unvested share-based payment awards	$ 6.3
Nonvested awards, total compensation cost not yet recognized, period for recognition	5 months