CONDENSED CONSOLIDATED STATEMENTS OF STOCKHOLDERS’ EQUITY - USD ($) $ in Thousands	Total	Cumulative Effect, Period of Adoption, Adjustment	Common Stock	Additional Paid-in Capital	Accumulated Deficit	Accumulated Deficit Cumulative Effect, Period of Adoption, Adjustment
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cumulative effect adjustment from adoption of new accounting pronouncement		$ (11,799)				$ (11,799)
Beginning balance (in shares) at Dec. 31, 2018			106,454,321
Beginning balance at Dec. 31, 2018	$ 243,745		$ 11	$ 387,233	$ (143,499)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock upon exercise of stock options and common stock warrants (in shares)			5,041,302
Issuance of common stock upon exercise of stock options and common stock warrants	14,145			14,145
Stock-based compensation expense	10,714			10,714
Issuance of common stock for settlement of RSUs (in shares)			123,562
Issuance of common stock for settlement of RSUs	$ 0
Issuance of common stock in connection with employee stock purchase plan (in shares)	280,308
Issuance of common stock in connection with employee stock purchase plan	$ 3,577			3,577
Net loss	(11,158)				(11,158)
Ending balance (in shares) at Sep. 30, 2019			111,899,493
Ending balance at Sep. 30, 2019	249,224		$ 11	415,669	(166,456)
Beginning balance (in shares) at Jun. 30, 2019			110,708,530
Beginning balance at Jun. 30, 2019	244,978		$ 11	407,876	(162,909)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock upon exercise of stock options and common stock warrants (in shares)			1,122,763
Issuance of common stock upon exercise of stock options and common stock warrants	3,795			3,795
Stock-based compensation expense	3,998			3,998
Issuance of common stock for settlement of RSUs (in shares)			68,200
Issuance of common stock for settlement of RSUs	0
Net loss	(3,547)				(3,547)
Ending balance (in shares) at Sep. 30, 2019			111,899,493
Ending balance at Sep. 30, 2019	249,224		$ 11	415,669	(166,456)
Beginning balance (in shares) at Dec. 31, 2019			113,604,398
Beginning balance at Dec. 31, 2019	259,424		$ 11	431,370	(171,957)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock upon exercise of stock options and common stock warrants (in shares)			6,744,484
Issuance of common stock upon exercise of stock options and common stock warrants	23,343		$ 1	23,342
Stock-based compensation expense	18,927			18,927
Issuance of common stock for settlement of RSUs (in shares)			1,162,183
Issuance of common stock for settlement of RSUs	0
Tides Foundation common stock warrant expense and other	1,011			1,011
Issuance of common stock in connection with employee stock purchase plan (in shares)			264,244
Issuance of common stock in connection with employee stock purchase plan	2,661			2,661
Net loss	(23,792)				(23,792)
Ending balance (in shares) at Sep. 30, 2020			121,775,309
Ending balance at Sep. 30, 2020	281,574		$ 12	477,311	(195,749)
Beginning balance (in shares) at Jun. 30, 2020			119,267,694
Beginning balance at Jun. 30, 2020	270,143		$ 12	463,133	(193,002)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock upon exercise of stock options and common stock warrants (in shares)			2,096,934
Issuance of common stock upon exercise of stock options and common stock warrants	7,333		$ 0	7,333
Stock-based compensation expense	6,734			6,734
Issuance of common stock for settlement of RSUs (in shares)			410,681
Issuance of common stock for settlement of RSUs	0
Tides Foundation common stock warrant expense and other	111			111
Net loss	(2,747)				(2,747)
Ending balance (in shares) at Sep. 30, 2020			121,775,309
Ending balance at Sep. 30, 2020	$ 281,574		$ 12	$ 477,311	$ (195,749)