Stockholders' Equity And Stock-Based Compensation (Narrative) (Details) - USD ($) $ / shares in Units, $ in Thousands		1 Months Ended	3 Months Ended		9 Months Ended
	Jan. 01, 2019	Jun. 30, 2020	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019	Nov. 30, 2017	Dec. 31, 2016	Dec. 31, 2014
Stockholders' Equity [Line Items]
Common stock, par value			$ 0.001		$ 0.001		$ 0.001
Proceeds from issuance of common stock under employee stock purchase plan					$ 490	$ 423
Common stock, shares issued			25,290,000		25,290,000		20,825,000
Options granted					1,933,560
Warrants exercised					85,750
Exercise price			$ 17.08		$ 17.08
Total stock-based compensation expense			$ 2,648	$ 2,679	$ 7,686	7,739
Cash received from option exercises					$ 349	272
2017 Employee Stock Purchase Plan [Member]
Stockholders' Equity [Line Items]
Common stock, shares issued			82,971		82,971
Shares authorized			250,000		250,000
Increase in shares available for issuance threshold of common stock outstanding, number of shares					450,000
Increase in shares available for issuance threshold of common stock outstanding, percent outstanding					1.50%
Shares available for grant			357,224		357,224
2017 Inducement Equity Incentive Plan [Member]
Stockholders' Equity [Line Items]
Term period					10 years
Shares authorized								1,000,000
Shares available for grant			26,283		26,283
2017 Plan [Member]
Stockholders' Equity [Line Items]
Term period					10 years
Shares authorized			1,500,000		1,500,000
Additional common stock reserved for issuance	833,018
Increase in shares available for issuance threshold of common stock outstanding, number of shares					1,200,000
Increase in shares available for issuance threshold of common stock outstanding, percent outstanding					4.00%
Shares available for grant			371,958		371,958
Rights Offering [Member]
Stockholders' Equity [Line Items]
Common stock, par value		$ 0.001
Price per share		$ 7.01
Value of warrants/rights		$ 30,000
Number of warrants to purchase shares of common stock		0.15
Net proceeds		$ 29,400
Warrants/rights outstanding		641,571	625,617		625,617
Exercise price of warrants/rights		$ 7.01
Redemption per warrant		$ 0.01
Period the warrants are exercisable after issuance					30 days
Percentage requirement for warrant redemption		200.00%
Period of time required for redemption of warrants					10 days
Period of time warrant not able to be redeemed					6 months
Number of common shares called by issuance of warrants		4,279,600
Rights Offering [Member] | Rights Offering [Member]
Stockholders' Equity [Line Items]
Common stock, par value		$ 0.001
Number of warrants to purchase shares of common stock		0.15
First Vesting Portion [Member] | 2017 Inducement Equity Incentive Plan [Member]
Stockholders' Equity [Line Items]
Vesting percentage					25.00%
General and administrative [Member]
Stockholders' Equity [Line Items]
Total stock-based compensation expense			$ 1,465	1,735	$ 4,729	4,881
Research and development [Member]
Stockholders' Equity [Line Items]
Total stock-based compensation expense			$ 1,183	$ 944	$ 2,957	$ 2,858
Initial Public Offering [Member] | Rights Offering [Member]
Stockholders' Equity [Line Items]
Warrants/rights outstanding			121,609		121,609
Private Placement [Member]
Stockholders' Equity [Line Items]
Common stock, par value										$ 0.001
Chairman, Robert W. Duggan [Member] | Rights Offering [Member]
Stockholders' Equity [Line Items]
Ownership percentage			47.00%		47.00%		43.00%
Shares purchased					2,561,873
Common Stock
Stockholders' Equity [Line Items]
Warrants exercised			85,000		86,000	99,000
Common Stock | Rights Offering [Member]
Stockholders' Equity [Line Items]
Warrants/rights outstanding			641,571		641,571
Robert W. Duggan [Member] | Rights Offering [Member]
Stockholders' Equity [Line Items]
Ownership percentage		43.00%	47.00%		47.00%
Number of common shares called by issuance of warrants		2,561,873
MDB Capital Group, LLC [Member] | Initial Public Offering [Member]
Stockholders' Equity [Line Items]
Price per share									$ 5.00
Exercisable period of warrants or rights					5 years
Number of common shares called by issuance of warrants									574,985
MDB Capital Group, LLC [Member] | Private Placement [Member]
Stockholders' Equity [Line Items]
Price per share										$ 2.67
Warrants/rights outstanding			46,238		46,238
Exercisable period of warrants or rights					7 years
Number of common shares called by issuance of warrants										299,625