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Stock-Based Compensation - Additional Information (Detail) $ in Millions |  | 3 Months Ended |  |
--- | --- | --- | --- | ---
Jun. 10, 2015 shares | Mar. 31, 2016 USD ($) Period shares | Dec. 31, 2015 shares | Jun. 12, 2013 shares
Employee Stock Purchase Plan |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |
Increase in shares of common stock authorized for issuance | 1,500,000 | 1,320,500 |  |
Aggregate number of shares of common stock reserved for future issuance |  | 1,551,390 |  |
Employee Stock Purchase Plan, offering period |  | 12 months |  |
Number of purchase periods within each offering period | Period |  | 2 |  |
Stock-based compensation, option to be granted at percentage of fair value of common stock |  | 85.00% |  |
2008 Equity Incentive Plan |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |
Increase in shares of common stock authorized for issuance | 5,000,000 |  |  |
Aggregate number of shares of common stock reserved for future issuance |  | 21,000,000 |  |
Stock-based compensation, option to be granted at percentage of fair value of common stock |  | 100.00% |  |
Employee Stock Purchase Plan, authorized shares for issuance |  |  |  | 19,540,940
Stock-based compensation, award term |  | 10 years |  |
Performance-based stock options, outstanding |  | 0 |  |
Outstanding options and other stock based awards |  | 15,941,000 | 14,119,000 |
Number of shares available for future issuance |  | 4,400,000 |  |
2008 Equity Incentive Plan | Stock Options |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |
Stock-based compensation, vesting period |  | 4 years |  |
2008 Equity Incentive Plan | Performance-based Stock or Cash Awards |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |
Employee Stock Purchase Plan, authorized shares for issuance |  | 500,000 |  |
Stock option plan granted on cash award | $ |  | $ 1.0 |  |
2008 Equity Incentive Plan | Restricted Stock Units (RSUs) |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |
Stock-based compensation, vesting period |  | 3 years |  |
Number of Restricted Stock Units Outstanding |  | 633,000 | 0 |

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