Condensed Statements of Shareholders' Equity (Deficit) - USD ($) $ in Thousands	Common Stock [Member]	Additional Paid-in Capital [Member]	Receivables from Stockholder [Member]	Retained Earnings [Member]	Total
Beginning balance, value at Dec. 31, 2019	$ 126	$ 568,496		$ (572,599)	$ (3,977)
Common Stock, Shares, Outstanding, Beginning Balance at Dec. 31, 2019	125,803
Share-based compensation expense		344			344
Share-based compensation expense, shares	201
Exercise of options		3			3
Exercise of options, shares	4
Sales of common stock	$ 17	8,329			8,346
Sales of common stock, shares	17,425
Net loss				(7,238)	(7,238)
Ending balance, value at Jun. 30, 2020	$ 143	577,172		(579,837)	(2,522)
Common Stock, Shares, Outstanding, Ending Balance at Jun. 30, 2020	143,433
Beginning balance, value at Dec. 31, 2019	$ 126	568,496		(572,599)	(3,977)
Common Stock, Shares, Outstanding, Beginning Balance at Dec. 31, 2019	125,803
Ending balance, value at Dec. 31, 2020	$ 153	601,224	(6,135)	(586,233)	$ 9,009
Common Stock, Shares, Outstanding, Ending Balance at Dec. 31, 2020	152,926				152,926
Beginning balance, value at Mar. 31, 2020	$ 131	570,128		(577,533)	$ (7,274)
Common Stock, Shares, Outstanding, Beginning Balance at Mar. 31, 2020	130,878
Share-based compensation expense		187			187
Share-based compensation expense, shares	201
Exercise of options		3			3
Exercise of options, shares	4
Sales of common stock	$ 12	6,854			6,866
Sales of common stock, shares	12,350
Net loss				(2,304)	(2,304)
Ending balance, value at Jun. 30, 2020	$ 143	577,172		(579,837)	(2,522)
Common Stock, Shares, Outstanding, Ending Balance at Jun. 30, 2020	143,433
Beginning balance, value at Dec. 31, 2020	$ 153	601,224	(6,135)	(586,233)	$ 9,009
Common Stock, Shares, Outstanding, Beginning Balance at Dec. 31, 2020	152,926				152,926
Share-based compensation expense	$ 2	9,533			$ 9,535
Share-based compensation expense, shares	2,140
Exercise of options	$ 1	2,509			2,510
Exercise of options, shares	1,340
Sales of common stock	$ 8	122,893	6,135		129,036
Sales of common stock, shares	7,554
Net loss				(21,193)	(21,193)
Ending balance, value at Jun. 30, 2021	$ 164	736,159		(607,426)	$ 128,897
Common Stock, Shares, Outstanding, Ending Balance at Jun. 30, 2021	163,960				163,960
Beginning balance, value at Mar. 31, 2021	$ 158	660,267		(592,464)	$ 67,961
Common Stock, Shares, Outstanding, Beginning Balance at Mar. 31, 2021	157,952
Share-based compensation expense	$ 2	7,895			7,897
Share-based compensation expense, shares	1,772
Exercise of options		429			429
Exercise of options, shares	269
Sales of common stock	$ 4	67,568			67,572
Sales of common stock, shares	3,967
Net loss				(14,962)	(14,962)
Ending balance, value at Jun. 30, 2021	$ 164	$ 736,159		$ (607,426)	$ 128,897
Common Stock, Shares, Outstanding, Ending Balance at Jun. 30, 2021	163,960				163,960