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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- 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

The cash inflow associated with the amount received from the stock plan during the 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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- Definition

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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- Definition

An excess of the fair value of the modified award over the fair value of the award immediately before the modification.

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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 ($) $ in Thousands	1 Months Ended	3 Months Ended
	Jan. 31, 2016	Mar. 31, 2016	Mar. 31, 2015
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Increased number of issuance of awards under the 2013 Plan	1,500,000
Number of shares available for issuance		1,300,000
Stock-based compensation expense		$ 10,143	$ 5,432
Stock option share exercised		33,000
Proceed from option share exercised		$ 500
Maximum [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock option share exercised		100,000
Research And Development Expense [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based compensation expense		$ 4,700	3,200
General And Administrative Expense [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based compensation expense		5,400	2,200
Stock Options [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based compensation expense		8,926	4,755
Unrecognized stock- based compensation expense related to unvested stock options, restricted stock awards and employee stock purchase plan		$ 105,300
Expected weighted-average period related to unvested stock options, restricted stock awards and employee stock purchase plan		3 years
Restricted Stock Units [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based compensation expense		$ 1,127	617
Unrecognized stock- based compensation expense related to unvested stock options, restricted stock awards and employee stock purchase plan		$ 105,300
Expected weighted-average period related to unvested stock options, restricted stock awards and employee stock purchase plan		3 years
Employee Stock Purchase Plan [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based compensation expense		$ 90	$ 60
Unrecognized stock- based compensation expense related to unvested stock options, restricted stock awards and employee stock purchase plan		$ 105,300
Expected weighted-average period related to unvested stock options, restricted stock awards and employee stock purchase plan		3 years
Common shares reserved for future issuance		238,000
Shares of common stock issued under plan		9,758	6,780
Employee Stock Option [Member] \| General And Administrative Expense [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based compensation expense recognized through modification of vesting condition		$ 300