Stockholders' Equity And Stock-Based Compensation (Tables)

9 Months Ended

Sep. 30, 2019

Stockholders' Equity [Line Items]

Summary Of Stock Option Activity

	Stock Options Outstanding
				Weighted-
		Weighted-		average
	Number	average		remaining life
	of shares	exercise price		(in years)
Balances — December 31, 2018	2,956,687	$	17.04	7.6
Options granted	917,182
Options exercised	(98,928)
Options canceled	(64,805)
Options expired	(164,645)
Balances — September 30, 2019	3,545,491	$	16.36
Exercisable — September 30, 2019	1,864,496	$	16.18

Summary Of Stock-Based Compensation Expense

	Three-Month Periods Ended				Nine-Month Periods Ended
	September 30,				September 30,
	2019		2018		2019		2018
General and administrative	$	1,735	$	2,483	$	4,881	$	7,533
Research and development		944		910		2,858		2,455
Total stock-based compensation expense	$	2,679	$	3,393	$	7,739	$	9,988

Options [Member]

Stockholders' Equity [Line Items]

Schedule Of Fair Value Of Employee Stock Options

	Three-Month Periods Ended September 30,		Nine-Month Periods Ended September 30,
	2019	2018	2019	2018
Expected term in years	5.8 - 6.1	6.1	0.4 - 6.1	5.3 - 6.1
Expected volatility	70%	70%	70%	70%
Risk-free interest rate	1.4 - 1.7%	2.9%	1.4 - 2.6%	2.7 - 2.9%
Dividend yield	—	—	—	—

2017 Employee Stock Purchase Plan [Member]

Stockholders' Equity [Line Items]

Schedule Of Fair Value Of Employee Stock Options

	Three-Month Periods Ended September 30,		Nine-Month Periods Ended September 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	1.7 - 1.9%	2.3 - 2.5%	1.7 - 2.6%	1.9 - 2.5%
Dividend yield	—	—	—	—