Stock-Based Compensation (Tables)

3 Months Ended

Mar. 31, 2021

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Schedule of Stock Option Activity

The following table summarizes the status of the Company’s stock option activity granted under the Plans to employees, directors, and consultants (aggregate intrinsic value in thousands):

	Stock Options			Weighted- Average Exercise price		Weighted- Average Remaining Contractual Term		Aggregate Intrinsic Value
Outstanding at December 31, 2020		12,496,888		$	9.26		5.42	$	22,463
Granted		20,000			11.90		—		—
Exercised		(119,425	)		7.10		—		—
Forfeited and expired		(32,830	)		12.92		—		—
Outstanding at March 31, 2021		12,364,633		$	9.28		5.20	$	—
Vested and exercisable at March 31, 2021		9,504,028		$	8.21		4.28	$	—

Schedule of Weighted-Average Assumptions Used as Inputs to Black-Scholes Option Pricing Model

The Company determines the fair value of stock-based awards on the grant date using the Black-Scholes option pricing model, which is impacted by assumptions regarding several highly subjective variables. The following table summarizes the weighted-average assumptions used as inputs to the Black-Scholes model during the periods indicated:

	Three Months Ended March 31,
	2021			2020
Weighted average grant date fair value	$	7.40		$	7.32
Expected dividend yield		—	%		—	%
Expected stock price volatility		68	%		67	%
Risk-free interest rate		1.37	%		0.75	%
Expected life of options (in years)		6.3			5.0

Schedule of Stock-Based Compensation Cost

The components of stock-based compensation and the amounts recorded within cost of sales, research and development expenses and selling, general, and administrative expenses in the Company’s consolidated statements of operations and comprehensive loss consisted of the following for the three months ended March 31, 2021 and 2020 (in thousands):

	Three Months Ended March 31,
	2021		2020
Stock options	$	2,205	$	1,864
Restricted stock expense		29		397
Employee stock purchase plan		46		70
Total stock-based compensation expense	$	2,280	$	2,331
Cost of sales	$	56	$	54
Research and development expenses		601		946
Selling, general, and administrative expenses		1,623		1,331
Total stock-based compensation expense	$	2,280	$	2,331