Stock-based Compensation (Tables)

12 Months Ended

Dec. 31, 2019

Disclosure of Compensation Related Costs, Share-based Payments [Abstract]

Summary of Weighted Average Assumptions Used to Value Options

	Year Ended December 31,
	2019		2018		2017
Volatility	65	%	72	%	86	%
Expected dividend yield	—		—		—
Risk-free rate	2.22	%	2.85	%	2.15	%
Expected term (in years)	6		6		6

Schedule of Employee Service Share-based Compensation for Stock Options, Restricted Stock Units and ESPP Shares

The following table presents the effects of stock-based compensation for stock options, RSUs, and ESPP (in thousands):

	Year Ended December 31,
	2019		2018		2017
Cost of revenue	$	290	$	190	$	112
Research and development		2,119		1,203		1,172
Selling, general and administrative		3,288		1,815		2,218
Total	$	5,697	$	3,208	$	3,502