Stock-Based Compensation - Additional Information (Detail) (USD $)	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Deferred Compensation Arrangement With Individual Share Based Payments [Line Items]
Common stock reserved, shares	935,213
Term of stock options granted		10 years
Vesting period of stock options	2 years 9 months 18 days	4 years
Number of common stock shares reserved for issuance under the 2013 Employee Stock Purchase Plan	6,949,108
Aggregate intrinsic value of options exercised	$ 12,500,000	$ 6,300,000	$ 451,000
Total estimated grant date fair value of options vested	9,000,000	3,800,000	3,000,000
Unamortized share based compensation expected to be recognized over the remaining vesting period	21,800,000
Weighted-average per share fair value of employee options granted	$ 15.73	$ 12.46	$ 5.90
Share based compensation, options weighted average exercise price	$ 25.96
Incentive Stock Options
Deferred Compensation Arrangement With Individual Share Based Payments [Line Items]
Exercise price of stock options granted as a minimum percentage of fair value of common stock		100.00%
Nonstatutory Stock Options
Deferred Compensation Arrangement With Individual Share Based Payments [Line Items]
Exercise price of stock options granted as a minimum percentage of fair value of common stock		85.00%
10% or more
Deferred Compensation Arrangement With Individual Share Based Payments [Line Items]
Exercise price of stock options granted as a minimum percentage of fair value of common stock		110.00%
Percentage of voting stock		10.00%
Nonemployee Stock Options
Deferred Compensation Arrangement With Individual Share Based Payments [Line Items]
Vesting period of stock options	4 years
Share based compensation, options granted	33,888	32,943	6,380
Share based compensation, options weighted average exercise price	$ 25.41	$ 19.88	$ 7.00
Stock-based compensation	$ 769,000	$ 775,000	$ 144,000
Employee Stock Purchase Plan
Deferred Compensation Arrangement With Individual Share Based Payments [Line Items]
Exercise price of stock options granted as a minimum percentage of fair value of common stock	85.00%
Number of common stock shares reserved for issuance under the 2013 Employee Stock Purchase Plan	1,000,000
Percentage increase in number of common stock outstanding	2.00%

Percentage of voting stock.

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Share based compensation arrangement by share based payment award increase in shares available for issuance percentage of total common stock outstanding.

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Stock option grants exercise price minimum percentage on fair market value.

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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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Aggregate number of common shares reserved for future issuance.

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Unrecognized cost of unvested share-based compensation awards.

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

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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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Fair value of options vested. Excludes equity instruments other than options, for example, but not limited to, share units, stock appreciation rights, restricted stock.

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

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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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