CONSOLIDATED STATEMENTS OF CHANGE IN EQUITY - USD ($) $ in Thousands	Common stock January Offering	Common stock June Offering	Common stock Over Allotment January	Common stock Over Allotment June	Common stock	Additional paid in capital January Offering	Additional paid in capital June Offering	Additional paid in capital Over Allotment January	Additional paid in capital Over Allotment June	Additional paid in capital	Accumulated other comprehensive loss	Accumulated deficit	January Offering	June Offering	Over Allotment January	Over Allotment June	Total
Balance at the beginning of the period, shares at Dec. 31, 2018					627,454,270
Balance at the beginning of the period at Dec. 31, 2018					$ 939					$ 574,208	$ (9,763)	$ (318,499)					$ 246,885
Increase (Decrease) in Stockholders' Equity
Issuance of shares upon exercise of stock options					$ 4					362							$ 366
Issuance of shares upon exercise of stock options (in shares)					3,549,298												3,549,298
Other comprehensive loss											2,499						$ 2,499
Share-based compensation expense										11,053							11,053
Net loss												(137,165)					(137,165)
Balance at the end of the period at Dec. 31, 2019					$ 943					585,623	(7,264)	(455,664)					123,638
Balance at the end of the period, shares at Dec. 31, 2019					631,003,568
Increase (Decrease) in Stockholders' Equity
Issuance of shares upon exercise of stock options					$ 14					5,649							$ 5,663
Issuance of shares upon exercise of stock options (in shares)					11,401,390												11,401,390
Issuance of shares upon completion of public offering, net of issuance costs	$ 165	$ 155	$ 24	$ 24		$ 78,451	$ 209,831	$ 11,914	$ 33,824				$ 78,616	$ 209,986	$ 11,938	$ 33,848
Issuance of shares upon completion of public offering, net of issuance costs (in shares)	126,000,000	123,000,000	18,900,000	18,450,000
Other comprehensive loss											(2,784)						$ (2,784)
Share-based compensation expense										10,414							10,414
Net loss												(130,092)					(130,092)
Balance at the end of the period at Dec. 31, 2020					$ 1,325					935,706	(10,048)	(585,756)					$ 341,227
Balance at the end of the period, shares at Dec. 31, 2020					928,754,958												928,754,958
Increase (Decrease) in Stockholders' Equity
Issuance of shares upon exercise of stock options					$ 8					751							$ 759
Issuance of shares upon exercise of stock options (in shares)					5,723,646												5,723,646
Issuance of shares upon completion of public offering, net of issuance costs (in shares)					3,069,330
Issue of shares under At The Market sales agreement, net of commission and expenses					$ 4					2,525							$ 2,529
Issue of shares under At The Market sales agreement, net of commission and expenses, shares					3,069,330
Other comprehensive loss											(1,094)						(1,094)
Share-based compensation expense										20,629							20,629
Net loss												(158,090)					(158,090)
Balance at the end of the period at Dec. 31, 2021					$ 1,337					$ 959,611	$ (11,142)	$ (743,846)					$ 205,960
Balance at the end of the period, shares at Dec. 31, 2021					937,547,934												937,547,934