XML 22 R12.htm IDEA: XBRL DOCUMENT
v3.10.0.1

Stock-Based Compensation | 9 Months Ended
--- | ---
Sep. 30, 2018
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract] |
Stock-Based Compensation |
5. | Stock-Based Compensation
Stock-based compensation expense was allocated to research and development and general and administrative expense as follows (in thousands):
|  | Three Months Ended September 30, |  |  | Nine Months Ended September 30, |
|  | 2018 |  |  | 2017 |  |  | 2018 |  |  | 2017 |
Research and development |  | $ | 8,465 |  |  | $ | 5,538 |  |  | $ | 22,729 |  |  | $ | 16,060 |
General and administrative |  |  | 5,858 |  |  |  | 4,090 |  |  |  | 15,703 |  |  |  | 11,548 |
Total stock-based compensation expense |  | $ | 14,323 |  |  | $ | 9,628 |  |  | $ | 38,432 |  |  | $ | 27,608 |
The assumptions used to estimate the fair value of stock options granted and purchases under the Company’s 2014 Employee Share Purchase Plan (“ESPP”) using the Black-Scholes option valuation model were as follows:
|  | Three Months Ended September 30, |  |  |  | Nine Months Ended September 30, |  |
|  | 2018 |  |  |  | 2017 |  |  |  | 2018 |  |  |  | 2017 |  |
Stock Options |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Expected term (in years) |  |  | 5.3 |  |  |  |  | 5.3 |  |  |  |  | 5.4 |  |  |  |  | 5.7 |  |
Expected volatility |  |  | 68.1 |  | % |  |  | 69.5 |  | % |  |  | 67.8 |  | % |  |  | 71.5 |  | %
Risk-free interest rate |  |  | 2.9 |  | % |  |  | 1.9 |  | % |  |  | 2.7 |  | % |  |  | 2.2 |  | %
Expected dividend yield |  |  | — |  |  |  |  | — |  |  |  |  | — |  |  |  |  | — |  |
Weighted average estimated fair value |  | $ | 35.99 |  |  |  | $ | 26.47 |  |  |  | $ | 32.37 |  |  |  | $ | 16.63 |  |
ESPPs |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Expected term (in years) |  | 0.5 - 2.0 |  |  |  | 0.5 - 2.0 |  |  |  | 0.5 - 2.0 |  |  |  | 0.5 - 2.0 |  |
Expected volatility |  | 47.3 - 72.8 |  | % |  | 52.8 - 76.0 |  | % |  | 47.3 - 75.3 |  | % |  | 52.8 - 77.2 |  | %
Risk-free interest rate |  | 1.0 - 2.6 |  | % |  | 0.6 - 1.3 |  | % |  | 0.8 - 2.6 |  | % |  | 0.5 - 1.3 |  | %
Expected dividend yield |  |  | — |  |  |  |  | — |  |  |  |  | — |  |  |  |  | — |  |
Weighted average estimated fair value |  | $ | 20.10 |  |  |  | $ | 9.67 |  |  |  | $ | 15.27 |  |  |  | $ | 9.15 |  |

X
- Definition The entire disclosure for compensation-related costs for equity-based compensation, which may include disclosure of policies, compensation plan details, allocation of equity compensation, incentive distributions, equity-based arrangements to obtain goods and services, deferred compensation arrangements, employee stock ownership plan details and employee stock purchase plan details. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -URI http://asc.fasb.org/topic&trid=2228938 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 50 -URI http://asc.fasb.org/subtopic&trid=2208855 + Details
Name: | us-gaap_DisclosureOfCompensationRelatedCostsShareBasedPaymentsTextBlock
Namespace Prefix: | us-gaap_
Data Type: | nonnum:textBlockItemType
Balance Type: | na
Period Type: | duration

X
- References No definition available. + Details
Name: | us-gaap_DisclosureOfCompensationRelatedCostsSharebasedPaymentsAbstract
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration