XML 58 R33.htm IDEA: XBRL DOCUMENT v3.20.4
Stock-Based Compensation (Tables)
12 Months Ended
Dec. 31, 2020
Share-based Payment Arrangement [Abstract]  
Schedule of Fair Value of Employee Stock Options Estimated Using Weighted Average Assumptions
The fair value of employee and director stock options was estimated at the date of grant using the Black-Scholes option pricing model with the weighted average assumptions below.
Year Ended Year ended December 31,
20192018
Expected term (in years)6.16.1
Expected volatility45.0 %45.7 %
Risk-free interest rate2.39 %2.75 %
Dividend yield— %— %
The fair value of market based RSUs was estimated at the date of grant using the Monte-Carlo option pricing model with the assumptions below. Additional details on the Company's market based RSUs are included below.
Year Ended
December 31,
2020
Expected term (in years)0.74
Expected volatility63.0 %
Risk-free interest rate0.17 %
Dividend yield— %
Summary of Stock-Based Compensation Expense Included in Consolidated 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):

Year Ended December 31
202020192018
Cost of revenue$27 $658 $193 
Research and development7,727 4,462 3,057 
Selling, general and administrative33,761 21,121 13,079 
Total stock-based compensation expense$41,515 $26,241 $16,329