Stock-based Compensation - Schedule of Stock Options Activity (Detail) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended
Mar. 31, 2015
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Options outstanding at December 31, 2013, Number of Shares	3,826,459
Granted, Number of Shares	765,800
Exercised, Number of Shares	(14,043)
Cancelled, Number of Shares	(29,356)
Options outstanding at September 30, 2014, Number of Shares	4,548,860
Options exercisable at September 30, 2014, Number of Shares	1,721,301
Options outstanding at December 31, 2013, Weighted Average Exercise Price	$ 8.39
Granted, Weighted Average Exercise Price	$ 28.29
Exercised, Weighted Average Exercise Price	$ 0.44
Cancelled, Weighted Average Exercise Price	$ 9.85
Options outstanding at September 30, 2014, Weighted Average Exercise Price	$ 11.71
Options exercisable at September 30, 2014, Weighted Average Exercise Price	$ 5.09
Options outstanding at December 31, 2013, Aggregate Intrinsic Value	$ 79,792
Options outstanding at September 30, 2014, Aggregate Intrinsic Value	89,292
Options exercisable at September 30, 2014, Aggregate Intrinsic Value	$ 45,188

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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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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.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 718

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (c)(1)(iii)

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The weighted-average price as of the balance sheet date at which grantees can acquire the shares reserved for issuance on vested portions of options outstanding and currently exercisable under the stock option plan.

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The number of shares under options that were cancelled during the reporting period as a result of occurrence of a terminating event specified in contractual agreements pertaining to the stock option plan.

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-Name Accounting Standards Codification

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-Subparagraph (c)(1)(iv)(3)

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

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Weighted average price at which grantees could have acquired the underlying shares with respect to stock options that were terminated.

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Weighted average per share amount at which grantees can acquire shares of common stock by exercise of options.

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

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