Stock-Based Compensation (Tables)

12 Months Ended

Dec. 31, 2019

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

Summary of Share Based Fair Value Assumptions

The fair value of options granted were estimated using the Black-Scholes-Merton option pricing model based on the assumptions in the table below:

	Year ended December 31,
	2019	2018
Expected dividend yield	0%	0%
Expected volatility	81% - 92%	73% - 75%
Risk-free interest rate	1.39% - 2.66%	2.35% - 3.02%
Expected life (in years)	5.5 - 6.1	5.5 - 6.1

Schedule of Stock Option Activity

The following table summarizes the Company’s stock option activity, including grants to non-employees, for the year ended December 31, 2019:

	Number of Shares		Weighted- Average Exercise Price		Weighted- Average Remaining Contractual Term (Years)
Options outstanding at December 31, 2018	1,529,964		$	31.45	7.82
Granted	623,272		29.79
Forfeited	(248,834	)	33.13
Cancelled	(43,525	)	38.67
Exercised	(29,919	)	18.00
Options Outstanding December 31, 2019	1,830,958		$	30.71	7.36

Schedule of Stock Options Outstanding

The following table summarizes information about stock options outstanding at December 31, 2019:

	Number of Shares	Weighted Average Exercise Price		Weighted Average Remaining Contractual Term (Years)
Exercisable at December 31, 2019	926,498	$	32.48	6.14
Vested or expected to vest at December 31, 2019	1,763,300	$	30.75	7.28