Stockholder's Equity (Tables)

3 Months Ended

Mar. 31, 2020

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Summary of Stock Option Activity

Activity under the Company’s stock option plan is set forth below:

						Weighted
						Average
				Weighted		Remaining		Aggregate
				Average		Contractual		Intrinsic
	Number of			Exercise		Life		Value
	Shares			Price		(in years)		(in thousands)
Balances, January 1, 2020		1,820,160		$	10.70
Options granted		383,107			11.47
Options cancelled		(23,463	)		52.69
Options exercised		(5,645	)		5.83
Balances, March 31, 2020		2,174,159		$	10.39		5.4	$	6,350
Outstanding and expected to vest as of March 31, 2020		2,121,788		$	10.41		5.4	$	6,346
Exercisable as of March 31, 2020		1,504,713		$	10.65		5.2	$	6,271

Summary of Fair Value of Employee Stock Options

The fair value of employee stock options was estimated using the Black-Scholes model with the following weighted-average assumptions:

	March 31,			March 31,
	2020			2019
Expected volatility		111.0	%		111.0	%
Risk-free interest rate		1.6	%		2.5	%
Dividend yield		0.0	%		0.0	%
Expected life (in years)		6.1			6.0