CONDENSED CONSOLIDATED STATEMENTS OF REDEEMABLE CONVERTIBLE PREFERRED STOCKAND STOCKHOLDERS’ EQUITY (DEFICIT) - 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)			3,918,539
Issuance of common stock upon exercise of stock options and common stock warrants	10,350			10,350
Stock-based compensation expense	6,716			6,716
Issuance of common stock for settlement of RSUs (in shares)			55,362
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	(7,611)				(7,611)
Ending balance (in shares) at Jun. 30, 2019			110,708,530
Ending balance at Jun. 30, 2019	244,978		$ 11	407,876	(162,909)
Beginning balance (in shares) at Mar. 31, 2019			106,729,758
Beginning balance at Mar. 31, 2019	231,741		$ 11	392,188	(160,458)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock upon exercise of stock options and common stock warrants (in shares)			3,645,434
Issuance of common stock upon exercise of stock options and common stock warrants	9,583			9,583
Stock-based compensation expense	2,528			2,528
Issuance of common stock for settlement of RSUs (in shares)			53,030
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	(2,451)				(2,451)
Ending balance (in shares) at Jun. 30, 2019			110,708,530
Ending balance at Jun. 30, 2019	244,978		$ 11	407,876	(162,909)
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)			4,647,550
Issuance of common stock upon exercise of stock options and common stock warrants	16,010		$ 1	16,009
Stock-based compensation expense	12,193			12,193
Issuance of common stock for settlement of RSUs (in shares)			751,502
Issuance of common stock for settlement of RSUs	0
Tides Foundation common stock warrant expense and other	900			900
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	(21,045)				(21,045)
Ending balance (in shares) at Jun. 30, 2020			119,267,694
Ending balance at Jun. 30, 2020	270,143		$ 12	463,133	(193,002)
Beginning balance (in shares) at Mar. 31, 2020			114,866,938
Beginning balance at Mar. 31, 2020	258,736		$ 11	440,703	(181,978)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock upon exercise of stock options and common stock warrants (in shares)			3,697,663
Issuance of common stock upon exercise of stock options and common stock warrants	12,845		$ 1	12,844
Stock-based compensation expense	6,866			6,866
Issuance of common stock for settlement of RSUs (in shares)			438,849
Issuance of common stock for settlement of RSUs	0
Tides Foundation common stock warrant expense and other	59			59
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	(11,024)				(11,024)
Ending balance (in shares) at Jun. 30, 2020			119,267,694
Ending balance at Jun. 30, 2020	$ 270,143		$ 12	$ 463,133	$ (193,002)