Stockholders' Equity And Stock-Based Compensation (Tables)

6 Months Ended

Jun. 30, 2020

Stockholders' Equity [Line Items]

Summary Of Stock Option Activity

	Stock Options Outstanding
			Weighted
	Number		average
	of shares		exercise price
Balances — December 31, 2019	3,749,186	$	16.18
Options granted	1,823,810
Options exercised	(750)
Options canceled	(309,190)
Options expired	(46,556)
Balances — June 30, 2020	5,216,500	$	14.20
Exercisable — June 30, 2020	2,468,093	$	16.58

Summary Of Stock-Based Compensation Expense

	Three-Month Periods Ended				Six-Month Periods Ended
	June 30,				June 30,
	2020		2019		2020		2019
General and administrative	$	1,515	$	1,660	$	3,264	$	3,145
Research and development		897		1,039		1,774		1,915
Total stock-based compensation expense	$	2,412	$	2,699	$	5,038	$	5,060

Employee Stock Option [Member]

Stockholders' Equity [Line Items]

Schedule Of Fair Value Of Employee Stock Options

	Three-Month Periods Ended June 30,		Six-Month Periods Ended June 30,
	2020	2019	2020	2019
Expected term in years	5.3 - 6.1	5.3 - 6.1	5.3 - 6.1	0.4 - 6.1
Expected volatility	70%	70%	70%	70%
Risk-free interest rate	0.4 – 0.5%	1.9 - 2.4%	0.4 – 0.5%	1.9 - 2.6%
Dividend yield	—	—	—	—

2017 Employee Stock Purchase Plan [Member]

Stockholders' Equity [Line Items]

Schedule Of Fair Value Of Employee Stock Options

	Three-Month Periods Ended June 30,		Six-Month Periods Ended June 30,
	2020	2019	2020	2019
Expected term in years	0.5 - 1.0	0.5 - 1.0	0.5 - 1.0	0.5 - 1.0
Expected volatility	70%	70%	70%	70%
Risk-free interest rate	0.9 – 1.0%	2.5 - 2.6%	0.9 – 1.0%	2.5 - 2.6%
Dividend yield	—	—	—	—