UNAUDITED CONDENSED CONSOLIDATED STATEMENTS OF CHANGES IN STOCKHOLDERS' EQUITY - USD ($) $ in Thousands	Total	COMMON STOCK	ADDITIONAL PAID-IN CAPITAL	ACCUMULATED DEFICIT	ACCUMULATED OTHER COMPREHENSIVE INCOME	Public offering	Public offering COMMON STOCK	Public offering ADDITIONAL PAID-IN CAPITAL	At-the-market offering	At-the-market offering COMMON STOCK	At-the-market offering ADDITIONAL PAID-IN CAPITAL
Beginning balance (in shares) at Dec. 31, 2018		57,034,154
Beginning balance at Dec. 31, 2018	$ 27,277	$ 6	$ 299,596	$ (272,388)	$ 63
Increase (Decrease) in Shareholders' Equity
Net Loss	(8,679)			(8,679)
Unrealized Gain (Loss) on Available-for-Sale Investments	(7)				(7)
Foreign Currency Translation Adjustments	0				0
Vesting of / Delivery of common stock underlying Restricted Stock Units Issued, net of taxes withheld (in shares)		64,173
Vesting of Restricted Stock Units Issued, net of taxes withheld	(95)	$ 0	(95)
Exercise of employee stock options, net of tax (in shares)		30,000
Exercise of Employee Stock Options, Net of Tax	148	$ 0	148
Stock-based Compensation expense	1,517		1,517
End balance (in shares) at Mar. 31, 2019		57,128,327
End balance at Mar. 31, 2019	20,161	$ 6	301,166	(281,067)	56
Beginning balance (in shares) at Dec. 31, 2018		57,034,154
Beginning balance at Dec. 31, 2018	27,277	$ 6	299,596	(272,388)	63
Increase (Decrease) in Shareholders' Equity
Net Loss	(26,826)
Unrealized Gain (Loss) on Available-for-Sale Investments	10
Foreign Currency Translation Adjustments	(1)
End balance (in shares) at Sep. 30, 2019		63,887,384
End balance at Sep. 30, 2019	23,702	$ 6	322,837	(299,214)	73
Beginning balance (in shares) at Dec. 31, 2018		57,034,154
Beginning balance at Dec. 31, 2018	$ 27,277	$ 6	299,596	(272,388)	63
Increase (Decrease) in Shareholders' Equity
Issuance of common stock, net of offering costs (in shares)									1,840,443
End balance (in shares) at Dec. 31, 2019	65,378,890	65,378,890
End balance at Dec. 31, 2019	$ 20,320	$ 7	326,777	(306,516)	52
Beginning balance (in shares) at Mar. 31, 2019		57,128,327
Beginning balance at Mar. 31, 2019	20,161	$ 6	301,166	(281,067)	56
Increase (Decrease) in Shareholders' Equity
Net Loss	(10,292)			(10,292)
Unrealized Gain (Loss) on Available-for-Sale Investments	12				12
Foreign Currency Translation Adjustments	0				0
Issuance of common stock, net of offering costs (in shares)							5,833,334			437,043
Issuance of common stock, net of offering costs						$ 16,120	$ 0	$ 16,120	$ 2,089	$ 0	$ 2,089
Stock-based Compensation expense	1,502		1,502
End balance (in shares) at Jun. 30, 2019		63,398,704
End balance at Jun. 30, 2019	29,592	$ 6	320,877	(291,359)	68
Increase (Decrease) in Shareholders' Equity
Net Loss	(7,855)			(7,855)
Unrealized Gain (Loss) on Available-for-Sale Investments	6				6
Foreign Currency Translation Adjustments	(1)				(1)
Issuance of common stock, net of offering costs (in shares)							425,880
Issuance of common stock, net of offering costs						1,169	$ 0	1,169
Vesting of / Delivery of common stock underlying Restricted Stock Units Issued, net of taxes withheld (in shares)		62,800
Vesting of Restricted Stock Units Issued, net of taxes withheld	(85)	$ 0	(85)
Stock-based Compensation expense	876		876
End balance (in shares) at Sep. 30, 2019		63,887,384
End balance at Sep. 30, 2019	$ 23,702	$ 6	322,837	(299,214)	73
Beginning balance (in shares) at Dec. 31, 2019	65,378,890	65,378,890
Beginning balance at Dec. 31, 2019	$ 20,320	$ 7	326,777	(306,516)	52
Increase (Decrease) in Shareholders' Equity
Net Loss	(7,984)			(7,984)
Unrealized Gain (Loss) on Available-for-Sale Investments	(7)				(7)
Foreign Currency Translation Adjustments	6				6
Issuance of common stock, net of offering costs (in shares)							3,670,212
Issuance of common stock, net of offering costs						8,003	$ 0	8,003
Issuance of Warrants related to Debt Financing	501		501
Stock-based Compensation expense	935		935
End balance (in shares) at Mar. 31, 2020		69,049,102
End balance at Mar. 31, 2020	$ 21,774	$ 7	336,216	(314,500)	51
Beginning balance (in shares) at Dec. 31, 2019	65,378,890	65,378,890
Beginning balance at Dec. 31, 2019	$ 20,320	$ 7	326,777	(306,516)	52
Increase (Decrease) in Shareholders' Equity
Net Loss	(22,227)
Unrealized Gain (Loss) on Available-for-Sale Investments	(11)
Foreign Currency Translation Adjustments	$ 8
Issuance of common stock, net of offering costs (in shares)									1,128,608
End balance (in shares) at Sep. 30, 2020	93,573,165	93,573,165
End balance at Sep. 30, 2020	$ 42,075	$ 9	370,760	(328,743)	49
Beginning balance (in shares) at Mar. 31, 2020		69,049,102
Beginning balance at Mar. 31, 2020	21,774	$ 7	336,216	(314,500)	51
Increase (Decrease) in Shareholders' Equity
Net Loss	(6,893)			(6,893)
Unrealized Gain (Loss) on Available-for-Sale Investments	(6)				(6)
Foreign Currency Translation Adjustments	1				1
Issuance of common stock, net of offering costs (in shares)										987,716
Issuance of common stock, net of offering costs									$ 1,978	$ 0	1,978
Vesting of / Delivery of common stock underlying Restricted Stock Units Issued, net of taxes withheld (in shares)		120,104
Vesting of Restricted Stock Units Issued, net of taxes withheld	(19)	$ 0	(19)
Warrant Modification Expense	837		837
Stock-based Compensation expense	(1,461)		(1,461)
End balance (in shares) at Jun. 30, 2020		70,156,922
End balance at Jun. 30, 2020	16,211	$ 7	337,551	(321,393)	46
Increase (Decrease) in Shareholders' Equity
Net Loss	(7,350)			(7,350)
Unrealized Gain (Loss) on Available-for-Sale Investments	2				2
Foreign Currency Translation Adjustments	1				1
Issuance of common stock, net of offering costs (in shares)							23,178,809			140,892
Issuance of common stock, net of offering costs						$ 32,677	$ 2	$ 32,675	$ 284	$ 0	$ 284
Vesting of / Delivery of common stock underlying Restricted Stock Units Issued, net of taxes withheld (in shares)		96,542
Vesting of Restricted Stock Units Issued, net of taxes withheld	0	$ 0
Stock-based Compensation expense	$ 250		250
End balance (in shares) at Sep. 30, 2020	93,573,165	93,573,165
End balance at Sep. 30, 2020	$ 42,075	$ 9	$ 370,760	$ (328,743)	$ 49