Stockholders' Equity And Stock-Based Compensation (Tables)

6 Months Ended

Jun. 30, 2019

Stockholders' Equity [Line Items]

Summary Of Stock Option Activity

	Stock Options Outstanding
			Weighted
	Number		average
	of shares		exercise price
Balances — December 31, 2018	2,956,687	$	17.04
Options granted	487,932
Options exercised	(98,928)
Options canceled	(19,430)
Options expired	(153,958)
Balances — June 30, 2019	3,172,303	$	16.83
Exercisable —June 30, 2019	1,670,830	$	16.11

Summary Of Stock-Based Compensation Expense

	Three-Month Periods Ended				Six-Month Periods Ended
	June 30,				June 30,
	2019		2018		2019		2018
General and administrative	$	1,660	$	2,351	$	3,145		5,050
Research and development		1,039		824		1,915		1,545
Total stock-based compensation expense	$	2,699	$	3,175	$	5,060	$	6,595

Options outstanding [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,
	2019	2018	2019	2018
Expected term in years	5.3 - 6.1	5.3 - 6.1	0.4 - 6.1	5.3 - 6.1
Expected volatility	70%	70%	70%	70%
Risk-free interest rate	1.9 - 2.4%	2.7 - 3.0%	1.9 - 2.6%	2.7 - 3.0%
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,
	2019	2018	2019	2018
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	2.5 - 2.6%	1.9%	2.5 - 2.6%	1.9%
Dividend yield	—	—	—	—