XML 38 R28.htm IDEA: XBRL DOCUMENT v3.19.1
Stock-Based Compensation (Tables)
3 Months Ended
Mar. 31, 2019
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]  
Schedule of Fair Value of Employee and Director Stock Options Estimated Using Weighted Average Assumptions

The fair value of employee and director stock options was estimated at the date of grant using a Black-Scholes option valuation model with the weighted average assumptions below.

 

 

Three Months Ended

March 31,

 

 

 

2019

 

 

2018

 

Expected term (in years)

 

 

6.1

 

 

 

6.1

 

Expected volatility

 

 

45.0

%

 

 

45.9

%

Risk-free interest rate

 

 

2.40

%

 

 

2.72

%

Dividend yield

 

 

0.0

%

 

 

0.0

%

 

Summary of Total Stock-Based Compensation Expense Included in Statements of Operations and Comprehensive Loss

The following table summarizes the total stock-based compensation expense included in the statements of operations and comprehensive loss for all periods presented (in thousands):

 

 

Three Months Ended

March 31,

 

 

 

2019

 

 

2018

 

Cost of revenue

 

$

88

 

 

$

117

 

Research and development

 

 

873

 

 

 

576

 

Selling, general and administrative

 

 

3,454

 

 

 

2,554

 

Total stock-based compensation expense

 

$

4,415

 

 

$

3,247