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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Unrecognized cost of unvested share-based compensation awards.

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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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Unrecognized cost of unvested options awarded to employees as compensation.

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The cash inflow associated with the amount received from the stock plan during the period.

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The number of grants made during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan).

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The number of equity-based payment instruments, excluding stock (or unit) options, that vested during the reporting period.

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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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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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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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The addition or reduction in the number of reserved shares that could potentially be issued under the option plan attributable to reasons other than grants, exercises, forfeitures, and expirations during the reporting period.

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Number of share instruments newly issued under a share-based compensation plan.

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Number of share options (or share units) exercised during the current period.

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Stock-based compensation - Additional Information (Detail) - USD ($)	1 Months Ended			3 Months Ended
	Feb. 28, 2018	Jan. 31, 2018	Jan. 31, 2017	Mar. 31, 2018	Mar. 31, 2017	Jun. 03, 2013
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Increased number of issuance of awards under the 2013 Plan		2,000,000	1,600,000
Number of shares available for issuance				2,000,000
Stock-based compensation expense				$ 22,995,000	$ 11,481,000
Stock option share exercised				301,000
Proceed from option share exercised				$ 19,700,000
Performance And Service Condition Based Restricted Stock Unit [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based compensation expense				$ 0
Restricted stock units issued to employees	300,000
Vested during period				0
Performance And Service Condition Based Restricted Stock Unit [Member] \| Maximum [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based compensation expense yet to recognize				$ 51,800,000
Stock Options [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based compensation expense				17,295,000	9,342,000
Unrecognized stock- based compensation expense related to unvested stock options, restricted stock awards and employee stock purchase plan				$ 295,900,000
Expected weighted-average period related to unvested stock options, restricted stock awards and employee stock purchase plan				3 years 2 months 12 days
Restricted Stock Units [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based compensation expense				$ 5,541,000	1,956,000
Restricted stock units issued to employees				522,000
Vested during period				74,000
Unrecognized stock- based compensation expense related to unvested stock options, restricted stock awards and employee stock purchase plan				$ 295,900,000
Expected weighted-average period related to unvested stock options, restricted stock awards and employee stock purchase plan				3 years 2 months 12 days
Employee Stock Purchase Plan [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based compensation expense				$ 159,000	$ 183,000
Unrecognized stock- based compensation expense related to unvested stock options, restricted stock awards and employee stock purchase plan				$ 295,900,000
Expected weighted-average period related to unvested stock options, restricted stock awards and employee stock purchase plan				3 years 2 months 12 days
Common shares reserved for future issuance						238,000
Shares of common stock issued under plan				9,055	11,079