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Stockholders' Equity - Additional Information (Detail) - USD ($) |  |  |  |  | 12 Months Ended
--- | --- | --- | --- | --- | ---
Oct. 24, 2016 | Jun. 16, 2015 | Jan. 28, 2014 | Jun. 28, 2012 | Dec. 31, 2016 | Dec. 31, 2015 | Dec. 31, 2014
Class of Stock [Line Items] |  |  |  |  |  |  |
Preferred stock, shares authorized |  |  |  |  | 10,000,000 | 10,000,000 |
Preferred stock, par value |  |  |  |  | $ 0.0001 | $ 0.0001 |
Preferred stock, shares designated |  |  |  |  | 0 | 0 |
Preferred stock, shares issued |  |  |  |  | 0 | 0 |
Preferred stock, shares outstanding |  |  |  |  | 0 | 0 |
Proceeds from sale of common stock | $ 189,700,000 |  | $ 117,200,000 |  |  |  |
Common stock, shares authorized |  |  |  |  | 300,000,000 | 300,000,000 |
Maximum 401(k) per employee, percentage of annual salary |  |  |  |  | 60.00% |  |
Compensation expense in connection with 401(k) retirement plan |  |  |  |  | $ 1,100,000 | $ 900,000 | $ 900,000
Change in control severance payment period for executives |  |  |  |  | 12 months |  |
Change in control severance payment period for employees |  |  |  |  | 6 months |  |
Change in control cash severance payment for chief executive officer |  |  |  |  | 24 months base salary plus annual target incentive pay |  |
Employee Stock Purchase Plan [Member] |  |  |  |  |  |  |
Class of Stock [Line Items] |  |  |  |  |  |  |
Common stock, shares authorized |  |  |  |  | 2,500,000 |  |
Percentage of purchase price of stock |  |  |  |  | 85.00% |  |
Maximum [Member] |  |  |  |  |  |  |
Class of Stock [Line Items] |  |  |  |  |  |  |
Matching 401(k) employer contribution, maximum amount |  |  |  |  | $ 3,000 |  |
2012 Performance Incentive Plan [Member] |  |  |  |  |  |  |
Class of Stock [Line Items] |  |  |  |  |  |  |
Additional new shares available for award grants |  | 7,000,000 |  | 5,300,000 |  |  |
Share-based compensation plan's share limit reduction for every one restricted stock unit granted |  |  |  |  | 1.5 |  |
2012 Performance Incentive Plan [Member] | Maximum [Member] |  |  |  |  |  |  |
Class of Stock [Line Items] |  |  |  |  |  |  |
Number of common stock shares available for stock options grants |  |  |  |  | 19,936,433 |  |
Stock options term under equity incentive plans |  |  |  |  | 8 years |  |
2012 Performance Incentive Plan [Member] | Employee [Member] |  |  |  |  |  |  |
Class of Stock [Line Items] |  |  |  |  |  |  |
Service period for stock-based compensation award granted |  |  |  |  | 3 years |  |
2012 Performance Incentive Plan [Member] | Director [Member] |  |  |  |  |  |  |
Class of Stock [Line Items] |  |  |  |  |  |  |
Service period for stock-based compensation award granted |  |  |  |  | 1 year |  |
2012 Performance Incentive Plan [Member] | Stock Options [Member] | Employee [Member] |  |  |  |  |  |  |
Class of Stock [Line Items] |  |  |  |  |  |  |
Service period for stock-based compensation award granted |  |  |  |  | 4 years |  |
2012 Performance Incentive Plan [Member] | Stock Options [Member] | Director [Member] |  |  |  |  |  |  |
Class of Stock [Line Items] |  |  |  |  |  |  |
Service period for stock-based compensation award granted |  |  |  |  | 1 year |  |
2000 Non-Officer Equity Incentive Plan [Member] |  |  |  |  |  |  |
Class of Stock [Line Items] |  |  |  |  |  |  |
Stock options term under equity incentive plans |  |  |  |  | 8 years |  |
Common Shares [Member] |  |  |  |  |  |  |
Class of Stock [Line Items] |  |  |  |  |  |  |
Sale of common stock, Shares | 14,950,000 |  | 9,775,000 |  | 14,950,000 |  | 9,775,000
Underwriting commissions and discounts | $ 12,100,000 |  | $ 7,500,000 |  |  |  |
Legal, accounting fees, filing fees and other offering expenses | $ 400,000 |  | $ 600,000 |  |  |  |
Common stock, shares reserved for issuance in equity compensation plans |  |  |  |  | 24,772,837 |  |

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