Condensed Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands	Total	Series A Convertible Voting Preferred Stock [Member]	Common Stock [Member]	Additional Paid-In Capital [Member]	Accumulated Deficit [Member]
Stockholders Equity, Ending Balance at Dec. 31, 2018	$ 94,479		$ 74	$ 771,817	$ (677,412)
Stockholders Equity, Ending Balance, Shares at Dec. 31, 2018			1,859,120
Issuance of common stock for exercise of stock options	445			445
Issuance of common stock for exercise of stock options, Shares			8,056
Stock-based compensation	1,699			1,699
Net loss	(13,032)				(13,032)
Stockholders Equity, Ending Balance at Mar. 31, 2019	83,591		$ 74	773,961	(690,444)
Stockholders Equity, Ending Balance, Shares at Mar. 31, 2019			1,867,176
Stockholders Equity, Ending Balance at Dec. 31, 2018	94,479		$ 74	771,817	(677,412)
Stockholders Equity, Ending Balance, Shares at Dec. 31, 2018			1,859,120
Net loss	(40,813)
Stockholders Equity, Ending Balance at Sep. 30, 2019	58,848		$ 74	776,999	(718,225)
Stockholders Equity, Ending Balance, Shares at Sep. 30, 2019			1,867,176
Stockholders Equity, Ending Balance at Mar. 31, 2019	83,591		$ 74	773,961	(690,444)
Stockholders Equity, Ending Balance, Shares at Mar. 31, 2019			1,867,176
Stock-based compensation	1,758			1,758
Net loss	(14,878)				(14,878)
Stockholders Equity, Ending Balance at Jun. 30, 2019	70,471		$ 74	775,719	(705,322)
Stockholders Equity, Ending Balance, Shares at Jun. 30, 2019			1,867,176
Stock-based compensation	1,280			1,280
Net loss	(12,903)				(12,903)
Stockholders Equity, Ending Balance at Sep. 30, 2019	58,848		$ 74	776,999	(718,225)
Stockholders Equity, Ending Balance, Shares at Sep. 30, 2019			1,867,176
Stockholders Equity, Ending Balance at Dec. 31, 2019	86,345	$ 1	$ 74	851,957	(765,687)
Stockholders Equity, Ending Balance, Shares at Dec. 31, 2019		103,000	1,867,176
Conversion of Series A convertible voting preferred stock to common stock		$ (1)	$ 8	(7)
Conversion of Series A convertible voting preferred stock to common stock, Shares		(103,000)	7,803,273
Reclassification of warrant liabilities to equity	62,175			62,175
Issuance of common stock	8,782		$ 1	8,781
Issuance of common stock, Shares			725,283
Issuance of warrant in connection with an amendment to the asset purchase agreement	3,188			3,188
Stock-based compensation	918			918
Reverse stock split adjustment			$ (73)	73
Net loss	(31,912)				(31,912)
Stockholders Equity, Ending Balance at Mar. 31, 2020	129,496		$ 10	927,085	(797,599)
Stockholders Equity, Ending Balance, Shares at Mar. 31, 2020			10,395,732
Stockholders Equity, Ending Balance at Dec. 31, 2019	86,345	$ 1	$ 74	851,957	(765,687)
Stockholders Equity, Ending Balance, Shares at Dec. 31, 2019		103,000	1,867,176
Reclassification of warrant liabilities to equity	62,175
Net loss	(62,879)
Stockholders Equity, Ending Balance at Sep. 30, 2020	105,360		$ 10	933,916	(828,566)
Stockholders Equity, Ending Balance, Shares at Sep. 30, 2020			10,495,732
Stockholders Equity, Ending Balance at Mar. 31, 2020	129,496		$ 10	927,085	(797,599)
Stockholders Equity, Ending Balance, Shares at Mar. 31, 2020			10,395,732
Stock-based compensation	3,617			3,617
Net loss	(16,462)				(16,462)
Stockholders Equity, Ending Balance at Jun. 30, 2020	116,651		$ 10	930,702	(814,061)
Stockholders Equity, Ending Balance, Shares at Jun. 30, 2020			10,395,732
Issuance of common stock	1,140			1,140
Issuance of common stock, Shares			100,000
Stock-based compensation	2,074			2,074
Net loss	(14,505)				(14,505)
Stockholders Equity, Ending Balance at Sep. 30, 2020	$ 105,360		$ 10	$ 933,916	$ (828,566)
Stockholders Equity, Ending Balance, Shares at Sep. 30, 2020			10,495,732