CONSOLIDATED STATEMENTS OF CHANGES IN STOCKHOLDERS’ EQUITY - USD ($)	Total	Public offering	At -the-market	COMMON STOCK	COMMON STOCK Public offering	COMMON STOCK At -the-market	ADDITIONAL PAID-IN CAPITAL	ADDITIONAL PAID-IN CAPITAL Public offering	ADDITIONAL PAID-IN CAPITAL At -the-market	ACCUMULATED DEFICIT	ACCUMULATED OTHER COMPREHENSIVE INCOME / (LOSS)
Beginning balance (in shares) at Dec. 31, 2018				57,034,154
Beginning balance at Dec. 31, 2018	$ 27,277,000			$ 6,000			$ 299,596,000			$ (272,388,000)	$ 63,000
Increase (Decrease) in Shareholders' Equity
Net Loss	(34,128,000)									(34,128,000)
Unrealized Loss on Available-for-Sale Investments	(10,000)										(10,000)
Foreign Currency Translation Adjustments	$ (1,000)										(1,000)
Issuance of Common Stock (in shares)	30,000			30,000
Issuance of Common Stock	$ 147,900						148,000
Vesting of Restricted Stock Units Issued, net of taxes withheld (in shares)				215,079
Vesting of Restricted Stock Units Issued, net of taxes withheld	(279,000)						(279,000)
Issuance of Common Stock, net of Issuance costs/Public offering (in shares)					6,259,214	1,840,443
Issuance of Common Stock, net of Issuance Costs/Public offering		$ 17,288,000	$ 5,073,000		$ 1,000			$ 17,287,000	$ 5,073,000
Stock-based Compensation	$ 4,952,000						4,952,000
Ending balance (in shares) at Dec. 31, 2019	65,378,890			65,378,890
Ending balance at Dec. 31, 2019	$ 20,320,000			$ 7,000			326,777,000			(306,516,000)	52,000
Increase (Decrease) in Shareholders' Equity
Net Loss	(30,890,000)									(30,890,000)
Unrealized Loss on Available-for-Sale Investments	(3,000)										(3,000)
Foreign Currency Translation Adjustments	$ 8,000										8,000
Issuance of Common Stock (in shares)	0
Vesting of Restricted Stock Units Issued, net of taxes withheld (in shares)				216,646
Vesting of Restricted Stock Units Issued, net of taxes withheld	$ (19,000)						(19,000)
Issuance of Common Stock, net of Issuance costs/Public offering (in shares)					26,849,021	1,128,608
Issuance of Common Stock, net of Issuance Costs/Public offering		$ 40,679,000	$ 2,262,000		$ 2,000			$ 40,677,000	$ 2,262,000
Issuance of Warrants related to Debt Financing	501,000						501,000
Warrant Modification Expense	837,000						837,000
Stock-based Compensation	$ 475,000						475,000
Ending balance (in shares) at Dec. 31, 2020	93,573,165			93,573,165
Ending balance at Dec. 31, 2020	$ 34,170,000			$ 9,000			$ 371,510,000			$ (337,406,000)	$ 57,000