CONDENSED CONSOLIDATED STATEMENTS OF COVERTIBLE PREFERRED STOCK AND STOCKHOLDERS' EQUITY - USD ($)	Series A Convertible Preferred Stock	Series B Convertible Preferred Stock	2020 Public offering Common Stock	2020 Public offering Additional Paid- In Capital	2020 Public offering	Lincoln Park Capital Commitment Purchase Agreement Offering Member Common Stock	2019 Public Offering Common Stock	2019 Public Offering Additional Paid- In Capital	2019 Public Offering	Lincoln Park Capital Registered Offering Purchase Agreement Offering Member Common Stock	Lincoln Park Capital Registered Offering Purchase Agreement Offering Member Additional Paid- In Capital	Lincoln Park Capital Registered Offering Purchase Agreement Offering Member	Common Stock	Additional Paid- In Capital	Accumulated Other Comprehensive Income (loss)	Accumulated Deficit	Total
Balance at the beginning of the period (in shares) at Dec. 31, 2018													14,703,159
Increase (Decrease) in Shares Outstanding
Issuance of common stock through ATM sales (in shares)													1,033,147
Issuance of Series A & B Convertible Preferred Stock, net of underwriting discounts (in shares)						330,000	7,557,142			571,429
Balance at the end of the period (in shares) at Sep. 30, 2019													24,194,877
Balance at the beginning of the period at Dec. 31, 2018													$ 15,000	$ 162,393,000	$ 302,000	$ (153,535,000)	$ 9,175,000
Increase (Decrease) in Stockholders' Equity
Issuance of common stock through ATM sales													1,000	1,922,000			1,923,000
To record ATM issuance costs in additional paid-in-capital														(13,000)			(13,000)
Issuance of Series A & B Convertible Preferred Stock, net of underwriting discounts							$ 7,000	$ 12,115,000	$ 12,122,000	$ 1,000	$ 989,000	$ 990,000
Reclassification of 2017 warrants from liability to equity														11,822,000		(8,374,000)	3,448,000
Dividend attributable to down round feature of 2017 warrants									$ 359,000					359,000		(359,000)	359,000
Foreign currency translation adjustment															25,000		25,000
Stock-based compensation														2,796,000			2,796,000
Net loss																(24,904,000)	(24,904,000)
Balance at the end of the period at Sep. 30, 2019													$ 24,000	192,383,000	327,000	(187,172,000)	5,562,000
Balance at the beginning of the period (in shares) at Dec. 31, 2018													14,703,159
Balance at the end of the period (in shares) at Dec. 31, 2019	0	0											24,194,877
Balance at the beginning of the period at Dec. 31, 2018													$ 15,000	162,393,000	302,000	(153,535,000)	9,175,000
Balance at the end of the period at Dec. 31, 2019	$ 0	$ 0											$ 24,000	193,319,000	76,000	(195,168,000)	(1,749,000)
Balance at the beginning of the period (in shares) at Jun. 30, 2019													22,949,064
Increase (Decrease) in Shares Outstanding
Issuance of common stock through ATM sales (in shares)													344,384
Issuance of Series A & B Convertible Preferred Stock, net of underwriting discounts (in shares)										571,429
Balance at the end of the period (in shares) at Sep. 30, 2019													24,194,877
Balance at the beginning of the period at Jun. 30, 2019													$ 23,000	189,831,000	322,000	(179,237,000)	10,939,000
Increase (Decrease) in Stockholders' Equity
Issuance of common stock through ATM sales														617,000			617,000
To record ATM issuance costs in additional paid-in-capital														(4,000)			(4,000)
Issuance of Series A & B Convertible Preferred Stock, net of underwriting discounts						$ 330,000				$ 1,000	$ 989,000	$ 990,000
Foreign currency translation adjustment															5,000		5,000
Stock-based compensation														950,000			950,000
Net loss																(7,935,000)	(7,935,000)
Balance at the end of the period at Sep. 30, 2019													$ 24,000	192,383,000	327,000	(187,172,000)	$ 5,562,000
Balance at the beginning of the period (in shares) at Dec. 31, 2019	0	0											24,194,877
Increase (Decrease) in Shares Outstanding
Conversion of Series A Convertible Preferred Stock to prefunded warrants (in shares)	(1,421,801)
Conversion of Series B Convertible Preferred Stock to common stock (in shares)		(1,137,442)											11,374,420
Issuance of Series A & B Convertible Preferred Stock, net of underwriting discounts (in shares)	1,421,801	1,137,442	23,625,000
Issuance of common stock upon exercise of warrant (in shares)													273,954
Issuance of common stock upon exercise of stock options (in shares)													32,778				32,778
Balance at the end of the period (in shares) at Sep. 30, 2020	0	0											59,657,742
Balance at the beginning of the period at Dec. 31, 2019	$ 0	$ 0											$ 24,000	193,319,000	76,000	(195,168,000)	$ (1,749,000)
Increase (Decrease) in Stockholders' Equity
Issuance of common stock upon exercise of warrants														348,000			348,000
Series A & B Convertible Preferred Stock discount - beneficial conversion feature	5,226,000	4,173,000												(9,399,000)			(9,399,000)
Issuance of Series A & B Convertible Preferred Stock, net of underwriting discounts	14,062,000	11,260,000	$ 24,000	$ 48,252,000	$ 48,276,000
Series A & B Convertible Preferred Stock accrued dividends	(207,000)	(165,000)												(372,000)			(372,000)
Conversion of Series A & B Convertible Preferred Stock dividends to prefunded warrants and common stock	(207,000)	(165,000)											$ 1,000	371,000			372,000
Conversion of Series A & B Convertible Preferred Stock dividends to prefunded warrants and common stock													156,713
Conversion of Series A Convertible Preferred Stock to prefunded warrants	8,836,000													(8,836,000)			(8,836,000)
Conversion of Series B Convertible Preferred Stock to common stock		(7,087,000)											$ 11,000	7,076,000			7,087,000
Dividend attributable to down round feature of 2017 warrants														303,000		(303,000)	303,000
Issuance of common stock upon exercise of stock options														51,000			51,000
Foreign currency translation adjustment															(163,000)		(163,000)
Stock-based compensation														1,857,000			1,857,000
Net loss																(20,804,000)	(20,804,000)
Balance at the end of the period at Sep. 30, 2020	$ 0	$ 0											$ 60,000	269,440,000	(87,000)	(216,275,000)	53,138,000
Balance at the beginning of the period (in shares) at Jun. 30, 2020	0	0											59,657,742
Balance at the end of the period (in shares) at Sep. 30, 2020	0	0											59,657,742
Balance at the beginning of the period at Jun. 30, 2020	$ 0	$ 0											$ 60,000	268,770,000	121,000	(209,218,000)	59,733,000
Increase (Decrease) in Stockholders' Equity
Foreign currency translation adjustment															(208,000)		(208,000)
Stock-based compensation														670,000			670,000
Net loss																(7,057,000)	(7,057,000)
Balance at the end of the period at Sep. 30, 2020	$ 0	$ 0											$ 60,000	$ 269,440,000	$ (87,000)	$ (216,275,000)	$ 53,138,000