Stock-Based Compensation (Tables)

3 Months Ended

Mar. 31, 2020

Share-based Payment Arrangement [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 the Black-Scholes option pricing model with the weighted average assumptions below.

	Three Months Ended March 31,
	2019
Expected term (in years)	6.1
Expected volatility	45.0	%
Risk-free interest rate	2.40	%
Dividend yield	—	%

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,
	2020		2019
Cost of revenue	$	—	$	88
Research and development	741		873
Selling, general and administrative	(436)		3,895
Total stock-based compensation expense	$	305	$	4,856

Share-based Payment Arrangement, Performance Shares, Activity

The following table presents key terms of outstanding PRSU awards (in thousands except for share amounts and percentages):

Grant Year	PRSU Performance Period	Performance %	PRSU Shares Granted	Fair Value of PRSU Shares Granted		Cumulative Expense Recognized for PRSUs
2019	2018 - 2020	—%	159,314	$	15,160	$	—
2020	2019 - 2022	—%	133,834	10,993		—
			293,148	$	26,153	$	—