Share-Based Compensation - Summary of Option Activity (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
Mar. 31, 2020	Mar. 31, 2019	Mar. 31, 2018	Mar. 31, 2017
Number of Options
Beginning balance (in shares)	5,396,465	3,549,405	1,525,857
Granted (in shares)	2,992,200	2,246,410	2,338,116
Exercised (in shares)	(124,097)	(154,494)	(15,195)
Forfeited (in shares)	(541,266)	(244,856)	(299,373)
Ending balance (in shares)	7,723,302	5,396,465	3,549,405	1,525,857
Weighted Average Exercise Price
Beginning balance (in USD per share)	$ 14.46	$ 9.84	$ 5.06
Granted (in USD per share)	11.57	21.36	12.50
Exercised (in USD per share)	7.59	8.41	2.38
Forfeited (in USD per share)	17.60	14.59	6.64
Ending balance (in USD per share)	$ 9.25	$ 14.46	$ 9.84	$ 5.06
Options Vested and Expected to Vest
Number of Options (in shares)	7,723,302
Weighted Average Exercise Price (in USD per share)	$ 9.25
Weighted Average Remaining Contractual Life (in years)	8 years 29 days
Aggregate Intrinsic Value (in thousands)	$ 4,146
Additional Information
Options outstanding, Weighted Average Remaining Contractual Life	8 years 29 days	8 years 6 months 3 days	9 years 7 days	9 years 6 months 7 days
Options outstanding, Aggregate Intrinsic Value	$ 4,146	$ 50,878	$ 40,557	$ 10,255
Options exercisable, Number of Options (in shares)	3,009,080	1,581,810	502,361
Options exercisable, Weighted Average Exercise Price (in USD per share)	$ 8.13
Options exercisable, Weighted Average Remaining Contractual Life	7 years 3 months 18 days
Options exercisable, Aggregate Intrinsic Value	$ 3,686

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The number of shares into which fully or partially vested stock options outstanding as of the balance sheet date can be currently converted under the option plan.

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Gross number of share options (or share units) granted during the period.

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Amount by which the current fair value of the underlying stock exceeds the exercise price of options outstanding.

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Number of options outstanding, including both vested and non-vested options.

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Weighted average price at which grantees can acquire the shares reserved for issuance under the stock option plan.

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Amount by which current fair value of underlying stock exceeds exercise price of fully vested and expected to vest options outstanding. Includes, but is not limited to, unvested options for which requisite service period has not been rendered but that are expected to vest based on achievement of performance condition, if forfeitures are recognized when they occur.

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Number of fully vested and expected to vest options outstanding that can be converted into shares under option plan. Includes, but is not limited to, unvested options for which requisite service period has not been rendered but that are expected to vest based on achievement of performance condition, if forfeitures are recognized when they occur.

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Weighted average price at which option holders acquired shares when converting their stock options into shares.

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Amount of difference between fair value of the underlying shares reserved for issuance and exercise price of vested portions of options outstanding and currently exercisable.

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Weighted average remaining contractual term for vested portions of options outstanding and currently exercisable or convertible, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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