Consolidated Statements of Stockholders' Equity - USD ($)	Common Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	AOCI Attributable to Parent [Member]	Total
Beginning balance, value at Dec. 31, 2019	$ 836,000	$ 664,064,000	$ (486,470,000)		$ 178,430,000
Beginning balance, shares at Dec. 31, 2019	83,622,135
Stock option-based compensation expense		5,853,000			5,853,000
Restricted stock-based compensation expense		2,334,000			2,334,000
Issuance of common stock in connection with the exercise of stock options	$ 1,000	176,000			177,000
Issuance of common stock in connection with the exercise of stock options, shares	77,560
Issuance of common stock in connection with restricted share awards, net of cancellations	$ 34,000	(34,000)
Issuance of common stock in connection with restricted share awards, net of cancellations, shares	3,414,928
Issuance of common stock in connection with the exercise of pre-funded warrants	$ 90,000	(89,000)			1,000
Issuance of common stock in connection with the exercise of pre-funded warrants, shares	9,017,055
Net loss			(84,234,000)		(84,234,000)
Other comprehensive loss				(10,000)	(10,000)
Ending balance, value at Dec. 31, 2020	$ 961,000	672,304,000	(570,704,000)	(10,000)	102,551,000
Ending balance, shares at Dec. 31, 2020	96,131,678
Stock option-based compensation expense		5,250,000			5,250,000
Restricted stock-based compensation expense		3,666,000			3,666,000
Issuance of common stock in connection with the exercise of stock options	$ 6,000	825,000			831,000
Issuance of common stock in connection with the exercise of stock options, shares	630,675
Issuance of common stock in connection with restricted share awards, net of cancellations	$ 21,000	(21,000)
Issuance of common stock in connection with restricted share awards, net of cancellations, shares	2,071,275
Issuance of common stock for cash under open market sale agreement	$ 37,000	8,014,000			8,051,000
Issuance of common stock for cash under open market sale agreement, shares	3,671,794
Issuance of common stock and stock purchase warrants in connection with public offering, net of offering costs	$ 447,000	15,532,000			15,979,000
Issuance of common stock and stock purchase warrants in connection with public offering, net of offering costs, shares	44,700,000
Net loss			(84,936,000)		(84,936,000)
Other comprehensive loss				(17,000)	(17,000)
Ending balance, value at Dec. 31, 2021	$ 1,472,000	$ 705,570,000	$ (655,640,000)	$ (27,000)	$ 51,375,000
Ending balance, shares at Dec. 31, 2021	147,205,422