Condensed Consolidated Statements of Stockholders’ Equity - USD ($) $ in Thousands	Total	Public Offering	Private Placement	Common Shares	Common Shares Public Offering	Common Shares Private Placement	Additional Paid-in Capital	Additional Paid-in Capital Public Offering	Additional Paid-in Capital Private Placement	Accumulated Other Comprehensive Income	Accumulated Deficit
Beginning balance (in shares) at Dec. 31, 2020				26,883,000
Beginning balance at Dec. 31, 2020	$ 35,294			$ 27			$ 656,472			$ 0	$ (621,205)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock (in shares)					6,900,000	331,000
Issuance of common stock		$ 51,718	$ 3,377		$ 7			$ 51,711	$ 3,377
Issuance of common stock in connection with warrant exercises (in shares)				247,000
Issuance of common stock in connection with warrant exercises	3,092						3,092
Stock-based compensation expense related to equity-classified awards	1,204						1,204
Net loss	(22,122)										(22,122)
Ending balance (in shares) at Mar. 31, 2021				34,361,000
Ending balance at Mar. 31, 2021	72,563			$ 34			715,856			0	(643,327)
Beginning balance (in shares) at Dec. 31, 2020				26,883,000
Beginning balance at Dec. 31, 2020	35,294			$ 27			656,472			0	(621,205)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Unrealized gain/(loss) on available-for-sale securities	(2)
Net loss	(46,087)
Ending balance (in shares) at Sep. 30, 2021				34,374,000
Ending balance at Sep. 30, 2021	51,234			$ 34			718,494			(2)	(667,292)
Beginning balance (in shares) at Mar. 31, 2021				34,361,000
Beginning balance at Mar. 31, 2021	72,563			$ 34			715,856			0	(643,327)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock under employee stock purchase plan (in shares)				13,000
Issuance of common stock under employee stock purchase plan	68						68
Stock-based compensation expense related to equity-classified awards	1,169						1,169
Net loss	(13,597)										(13,597)
Ending balance (in shares) at Jun. 30, 2021				34,374,000
Ending balance at Jun. 30, 2021	60,203			$ 34			717,093			0	(656,924)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock-based compensation expense related to equity-classified awards	1,401						1,401
Unrealized gain/(loss) on available-for-sale securities	(2)									(2)
Net loss	(10,368)										(10,368)
Ending balance (in shares) at Sep. 30, 2021				34,374,000
Ending balance at Sep. 30, 2021	51,234			$ 34			718,494			(2)	(667,292)
Beginning balance (in shares) at Dec. 31, 2021				34,475,000
Beginning balance at Dec. 31, 2021	45,870			$ 34			720,386			(3)	(674,547)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock-based compensation expense related to equity-classified awards	1,267						1,267
Unrealized gain/(loss) on available-for-sale securities	4									4
Net loss	(10,199)										(10,199)
Ending balance (in shares) at Mar. 31, 2022				34,475,000
Ending balance at Mar. 31, 2022	36,942			$ 34			721,653			1	(684,746)
Beginning balance (in shares) at Dec. 31, 2021				34,475,000
Beginning balance at Dec. 31, 2021	$ 45,870			$ 34			720,386			(3)	(674,547)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Exercise of stock options (in shares)	9,833
Unrealized gain/(loss) on available-for-sale securities	$ 3
Net loss	(21,784)
Ending balance (in shares) at Sep. 30, 2022				34,621,000
Ending balance at Sep. 30, 2022	28,845			$ 35			725,141			0	(696,331)
Beginning balance (in shares) at Mar. 31, 2022				34,475,000
Beginning balance at Mar. 31, 2022	36,942			$ 34			721,653			1	(684,746)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock under employee stock purchase plan (in shares)				136,000
Issuance of common stock under employee stock purchase plan	545						544
Exercise of stock options (in shares)				3,000
Exercise of stock options	16						16
Stock-based compensation expense related to equity-classified awards	1,406						1,406
Unrealized gain/(loss) on available-for-sale securities	(3)									(3)
Net loss	(8,319)										(8,319)
Ending balance (in shares) at Jun. 30, 2022				34,614,000
Ending balance at Jun. 30, 2022	30,587			$ 35			723,619			(2)	(693,065)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Exercise of stock options (in shares)				7,000
Exercise of stock options	36						36
Stock-based compensation expense related to equity-classified awards	1,486						1,486
Unrealized gain/(loss) on available-for-sale securities	2									2
Net loss	(3,266)										(3,266)
Ending balance (in shares) at Sep. 30, 2022				34,621,000
Ending balance at Sep. 30, 2022	$ 28,845			$ 35			$ 725,141			$ 0	$ (696,331)