Stock-Based Compensation (Tables)

12 Months Ended

Dec. 31, 2019

Share-based Payment Arrangement [Abstract]

Schedule of Fair Value of Employee Stock Options Estimated Using Weighted Average Assumptions

The fair value of employee stock options was estimated using the weighted average assumptions below. Each of these inputs is subjective and its determination generally requires significant judgment.

	Year Ended December 31
	2019		2018		2017
Expected term (in years)	6.1		6.1		6.1
Expected volatility	45.0	%	45.7	%	51.9	%
Risk-free interest rate	2.39	%	2.75	%	2.07	%
Dividend yield	0.0	%	0.0	%	0.0	%

Summary of Total Stock-Based Compensation Expense for Options, RSUs and ESPP 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 for all periods presented (in thousands):

	Year Ended December 31
	2019		2018		2017
Cost of revenue	$	658	$	193	$	589
Research and development	4,462		3,057		1,619
Selling, general and administrative	21,121		13,079		7,544
Total stock-based compensation expense	$	26,241	$	16,329	$	9,752