Condensed Consolidated Statements of Equity - USD ($) $ in Thousands	Common Stock [Member]	Additional Paid-in Capital [Member]	Treasury Stock [Member]	Accumulated Deficit [Member]	Total
Balance at Dec. 31, 2018	$ 84	$ 552,531	$ (234)	$ (528,345)	$ 24,036
Balance (in shares) at Dec. 31, 2018	83,911,855		41,309
Issuance of restricted stock (in shares)	23,000
Warrants issued with debt financing		993			993
Forfeiture of restricted stock (in shares)	(67,628)
Issuance of common stock in At-the-Market offerings (net of offering costs of $0.2 million)	$ 5	27,494			27,499
Issuance of common stock in At-the-Market offerings (net of offering costs of $0.2 million) (in shares)	4,715,000
Compensation in respect of restricted stock granted to employees, directors and consultants		1,882			1,882
Net loss				(35,156)	(35,156)
Balance at Mar. 31, 2019	$ 89	582,900	$ (234)	(563,501)	19,254
Balance (in shares) at Mar. 31, 2019	88,582,227		41,309
Balance at Dec. 31, 2019	$ 109	739,956	$ (234)	(701,216)	38,615
Balance (in shares) at Dec. 31, 2019	109,425,243		41,309
Issuance of common stock in connection with exercise of warrants		80			80
Issuance of common stock in connection with exercise of warrants (in shares)	19,750
Issuance of restricted stock	$ 1	(1)
Issuance of restricted stock (in shares)	774,300
Forfeiture of restricted stock (in shares)	(10,000)
Compensation in respect of restricted stock granted to employees, directors and consultants		11,068			11,068
Net loss				(51,116)	(51,116)
Balance at Mar. 31, 2020	$ 110	$ 751,103	$ (234)	$ (752,332)	$ (1,353)
Balance (in shares) at Mar. 31, 2020	110,209,293		41,309