Stock-Based Compensation - Additional Information (Detail) - USD ($)
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12 Months Ended |
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Oct. 08, 2015 |
Dec. 31, 2015 |
Dec. 31, 2014 |
Dec. 31, 2013 |
Jul. 17, 2015 |
| Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |
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| Vesting period |
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4 years
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| Expiration period |
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10 years
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| Risk-free interest rate basis |
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The risk-free interest rate was based on an average of the five and seven-year U.S. Treasury zero-coupon issues for each option grant date with maturities approximately equal to the option's expected term.
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| Purchase price of common stock by employees |
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85.00%
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| Maximum [Member] |
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| Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |
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| Stock options granted, weighted-average grant date fair value |
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$ 10.09
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$ 4.88
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$ 4.65
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| Employee Stock Purchase Plan [Member] |
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| Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |
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| Number of shares of common stock reserved for future issuance |
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800,000
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| Stock Issued During Period, Shares, Employee Stock Purchase Plans |
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0
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| Employee Stock Purchase Plan [Member] | Maximum [Member] |
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| Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |
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| Employee withholding percentage |
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15.00%
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| 2015 Plan [Member] |
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| Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |
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| Number of shares of common stock reserved for future issuance |
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800,000
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| Share-based compensation, increase in number of shares reserved and available for issuance as percentage under the plan |
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4.00%
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| Number of shares additionally authorized |
1,500,000
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| Number of shares authorized |
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6,762,129
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| Shares available for grant |
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1,842,769
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| Restricted Stock [Member] |
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| Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |
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| Unrecognized compensation expense, restricted stock |
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$ 15,400,000
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| Unrecognized compensation cost, recognition period |
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2 years 4 months 24 days
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| Options to Purchase Common Stock [Member] |
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| Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |
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| Unrecognized compensation cost, recognition period |
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2 years 4 months 24 days
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| Unrecognized compensation cost, stock options |
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$ 5,000,000
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| Stock options vested, fair value |
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$ 3,400,000
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$ 2,400,000
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$ 1,600,000
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| Stock options granted, weighted-average grant date fair value |
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$ 5.01
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$ 4.09
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$ 2.46
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