Stock-Based Compensation (Tables)

3 Months Ended

Mar. 31, 2020

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, 2019		10,916,936		$	8.88		5.68	$	69,785
Granted		55,045			7.32		—		—
Exercised		(70,200	)		4.84		—		—
Forfeited and expired		(58,550	)		14.45		—		—
Outstanding at March 31, 2020		10,843,231		$	8.87		5.47	$	—
Vested and exercisable at March 31, 2020		8,731,256		$	7.67		4.88	$	619

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			Three Months Ended
	March 31, 2020			March 31, 2019
Weighted average grant date fair value	$	7.32		$	8.03
Expected dividend yield		—	%		—	%
Expected stock price volatility		67	%		64	%
Risk-free interest rate		0.75	%		2.63	%
Expected life of options (in years)		5.0			6.3

Schedule of Stock-Based Compensation Cost

The components of stock-based compensation and the amounts recorded within 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, 2020 and 2019 (in thousands):

	Three Months Ended March 31,
	2020		2019
Stock options	$	1,864	$	1,693
Restricted stock expense		397		—
Employee stock purchase plan		70		85
Total stock-based compensation expense	$	2,331	$	1,778
Cost of sales	$	54	$	64
Research and development expenses		946		591
Selling, general, and administrative expenses		1,331		1,123
Total stock-based compensation expense	$	2,331	$	1,778