Share-Based Compensation - Additional Information (Detail) $ / shares in Units, $ in Thousands	3 Months Ended
Jun. 30, 2018 USD ($) CompensationPlan Installment $ / shares shares	Jun. 30, 2017 USD ($) $ / shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of share-based compensation plans \| CompensationPlan	4
Weighted average per share fair value of options granted to employees \| $ / shares	$ 15.64	$ 10.26
Total intrinsic value of options exercised	$ 20,400
Proceeds from exercises of share-based awards	4,500
Unrecognized share-based compensation expense	$ 47,400
Unrecognized share-based compensation expense, net of estimated forfeiture, period for recognition	3 years 2 months 1 day
Share-based compensation expense recognized	$ 5,181	$ 2,646
Employee share option agreements, modification expense	200	$ 300
Unvested Restricted Share Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized share-based compensation expense	$ 10,100
Unrecognized share-based compensation expense, net of estimated forfeiture, period for recognition	3 years 8 months 19 days
Unvested Restricted Share Units [Member] \| Non-Employee Director [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation arrangement by share-based payment award, vesting period	3 years
Unvested Restricted Share Units [Member] \| Employees [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of vesting installment for equity granted \| Installment	4
2015 Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of options available for future grant \| shares	6,849,866
2015 Employee Share Purchase Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of options available for future grant \| shares	1,000,000
Ordinary shares reserved and authorized for issuance \| shares	1,100,000
Authorized payroll deductions percentage	10.00%
Share-based compensation arrangement by share-based payment award, term	6 months
Percentage of fair market value of shares to be considered as share price	85.00%
Share-based compensation expense recognized	$ 200
2015 Employee Share Purchase Plan [Member] \| Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Authorized payroll deductions percentage	1.00%

Employee stock purchase plan authorized payroll deductions percentage.

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- Definition

Share-based compensation arrangement by share-based payment award, number of plans.

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- Definition

Share based compensation arrangement by share based payment award number of vesting installments.

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- Definition

Share based compensation arrangement by share based payment award plan modification expense.

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- Definition

Represents the expense recognized during the period arising from equity-based compensation arrangements (for example, shares of stock, unit, stock options or other equity instruments) with employees, directors and certain consultants qualifying for treatment as employees.

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- Definition

Unrecognized cost of unvested share-based compensation awards.

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- Definition

Weighted average period over which unrecognized compensation is expected to be recognized for equity-based compensation plans, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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- Definition

Amount of cash inflow from exercise of stock options granted under share-based compensation arrangement.

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- Definition

Period which an employee's right to exercise an award is no longer contingent on satisfaction of either a service condition, market condition or a performance condition, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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No definition available.

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- Definition

The highest percentage of annual salary that an employee is permitted to utilize with respect to the plan.

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- Definition

The maximum number of shares (or other type of equity) originally approved (usually by shareholders and board of directors), net of any subsequent amendments and adjustments, for awards under the equity-based compensation plan. As stock or unit options and equity instruments other than options are awarded to participants, the shares or units remain authorized and become reserved for issuance under outstanding awards (not necessarily vested).

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- Definition

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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- Definition

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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- Definition

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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- Definition

Period from grant date that an equity-based award expires, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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- Definition

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

+ References

No definition available.

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