Condensed Consolidated Statements of Stockholders’ Equity - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-in Capital	Accumulated Deficit
Beginning balance (in shares) at Dec. 31, 2020		148,615,351
Beginning balance at Dec. 31, 2020	$ 130,266	$ 1,476	$ 755,874	$ (627,084)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock from option exercises (in shares)		6,021
Issuance of common stock from option exercises	19		19
Stock-based compensation	8,494		8,494
Issuance of common stock from releases of restricted stock units (in shares)		1,209,870
Issuance of common stock from releases of restricted stock units	0	$ 12	(12)
Tax withholding paid on behalf of employees for stock-based awards	(1,473)		(1,473)
Issuance of common stock upon public offering, net (in shares)		11,856,500
Issuance of common stock upon public offering (net of offering cost of $3,991)	53,513	$ 119	53,394
Issuance of common stock from warrant exercises (in shares)		42,621
Issuance of common stock from warrant exercises	2		2
Reclassification of warrant liability to additional paid-in capital upon warrant exercises	327		327
Net loss	(26,743)			(26,743)
Ending balance (in shares) at Mar. 31, 2021		161,730,363
Ending balance at Mar. 31, 2021	164,405	$ 1,607	816,625	(653,827)
Beginning balance (in shares) at Dec. 31, 2020		148,615,351
Beginning balance at Dec. 31, 2020	130,266	$ 1,476	755,874	(627,084)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss	(57,719)
Ending balance (in shares) at Jun. 30, 2021		163,590,744
Ending balance at Jun. 30, 2021	139,051	$ 1,624	822,230	(684,803)
Beginning balance (in shares) at Mar. 31, 2021		161,730,363
Beginning balance at Mar. 31, 2021	164,405	$ 1,607	816,625	(653,827)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock from option exercises (in shares)		37,630
Issuance of common stock from option exercises	165		165
Stock-based compensation	6,455		6,455
Issuance of common stock from releases of restricted stock units (in shares)		1,738,516
Issuance of common stock from releases of restricted stock units	0	$ 17	(17)
Tax withholding paid on behalf of employees for stock-based awards	(1,286)		(1,286)
Issuance of common stock from warrant exercises (in shares)		2,431
Reclassification of warrant liability to additional paid-in capital upon warrant exercises	24		24
Issuance of common stock from employee stock purchase plan (in shares)		81,804
Issuance of common stock from employee stock purchase plan	264		264
Net loss	(30,976)			(30,976)
Ending balance (in shares) at Jun. 30, 2021		163,590,744
Ending balance at Jun. 30, 2021	139,051	$ 1,624	822,230	(684,803)
Beginning balance (in shares) at Dec. 31, 2021		179,206,456
Beginning balance at Dec. 31, 2021	169,795	$ 1,782	905,145	(737,132)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock from option exercises (in shares)		19,292
Issuance of common stock from option exercises	56		56
Stock-based compensation	5,032		5,032
Issuance of common stock from releases of restricted stock units (in shares)		1,216,278
Issuance of common stock from releases of restricted stock units	0	$ 12	(12)
Tax withholding paid on behalf of employees for stock-based awards	(1,604)		(1,604)
Net loss	(25,774)			(25,774)
Ending balance (in shares) at Mar. 31, 2022		180,442,026
Ending balance at Mar. 31, 2022	147,505	$ 1,794	908,617	(762,906)
Beginning balance (in shares) at Dec. 31, 2021		179,206,456
Beginning balance at Dec. 31, 2021	$ 169,795	$ 1,782	905,145	(737,132)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock from option exercises (in shares)	24,208
Net loss	$ (53,407)
Ending balance (in shares) at Jun. 30, 2022		180,997,543
Ending balance at Jun. 30, 2022	124,818	$ 1,800	913,557	(790,539)
Beginning balance (in shares) at Mar. 31, 2022		180,442,026
Beginning balance at Mar. 31, 2022	147,505	$ 1,794	908,617	(762,906)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock from option exercises (in shares)		4,916
Issuance of common stock from option exercises	11		11
Stock-based compensation	5,101		5,101
Issuance of common stock from releases of restricted stock units (in shares)		406,895
Issuance of common stock from releases of restricted stock units	0	$ 4	(4)
Tax withholding paid on behalf of employees for stock-based awards	(490)		(490)
Issuance of common stock from employee stock purchase plan (in shares)		143,706
Issuance of common stock from employee stock purchase plan	324	$ 2	322
Net loss	(27,633)			(27,633)
Ending balance (in shares) at Jun. 30, 2022		180,997,543
Ending balance at Jun. 30, 2022	$ 124,818	$ 1,800	$ 913,557	$ (790,539)