Condensed Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands	Total	Public Offering	At The Market Equity Offering	Common Stock	Common Stock Public Offering	Common Stock At The Market Equity Offering	Additional Paid-In Capital	Additional Paid-In Capital Public Offering	Additional Paid-In Capital At The Market Equity Offering	Accumulated Other Comprehensive Loss	Accumulated Deficit
Beginning balance (in shares) at Dec. 31, 2019				42,498,430
Beginning balance at Dec. 31, 2019	$ 99,000			$ 42			$ 437,976			$ (5,205)	$ (333,813)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock under ESPP (in shares)				38,147
Issuance of common stock under ESPP	699						699
RSU settlements, net of shares withheld (in shares)				139,552
RSU settlements, net of shares withheld	(1,507)						(1,507)
Issuance of common stock for services (in shares)				3,091
Issuance of common stock for services	66						66
Issuance of common stock for cash upon exercise of stock options (in shares)				44,861
Issuance of common stock for cash upon exercise of stock options	155						155
Issuance of common stock for cash upon exercise of warrants (in shares)				295,466
Issuance of common stock for cash upon exercise of warrants	6,299						6,299
Employee stock-based compensation expense	4,200						4,200
Foreign currency translation adjustment	(1,705)									(1,705)
Net loss	(5,823)										(5,823)
Ending balance (in shares) at Mar. 31, 2020				43,019,547
Ending balance at Mar. 31, 2020	101,384			$ 42			447,888			(6,910)	(339,636)
Beginning balance (in shares) at Dec. 31, 2019				42,498,430
Beginning balance at Dec. 31, 2019	99,000			$ 42			437,976			(5,205)	(333,813)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Foreign currency translation adjustment	853
Net loss	(15,199)
Ending balance (in shares) at Sep. 30, 2020				49,132,348
Ending balance at Sep. 30, 2020	268,644			$ 47			621,961			(4,352)	(349,012)
Beginning balance (in shares) at Dec. 31, 2019				42,498,430
Beginning balance at Dec. 31, 2019	99,000			$ 42			437,976			(5,205)	(333,813)
Ending balance (in shares) at Dec. 31, 2020				49,441,166
Ending balance at Dec. 31, 2020	277,679			$ 49			632,253			(2,096)	(352,527)
Beginning balance (in shares) at Mar. 31, 2020				43,019,547
Beginning balance at Mar. 31, 2020	101,384			$ 42			447,888			(6,910)	(339,636)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common shares, net of commissions and offering costs (in shares)					4,492,187	1,000,000
Issuance of common shares, net of commissions and offering costs		$ 134,584	$ 23,451		$ 4	$ 1		$ 134,580	$ 23,450
RSU settlements, net of shares withheld (in shares)				143,101
RSU settlements, net of shares withheld	(2,030)						(2,030)
Issuance of common stock for services (in shares)				2,992
Issuance of common stock for services	58						58
Issuance of common stock for cash upon exercise of stock options (in shares)				204,469
Issuance of common stock for cash upon exercise of stock options	1,962						1,962
Employee stock-based compensation expense	6,320						6,320
Foreign currency translation adjustment	1,596									1,596
Net loss	(6,558)										(6,558)
Ending balance (in shares) at Jun. 30, 2020				48,862,296
Ending balance at Jun. 30, 2020	260,767			$ 47			612,228			(5,314)	(346,194)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock under ESPP (in shares)				38,576
Issuance of common stock under ESPP	694						694
RSU settlements, net of shares withheld (in shares)				34,602
RSU settlements, net of shares withheld	(466)						(466)
Issuance of common stock for services (in shares)				2,731
Issuance of common stock for services	96						96
Issuance of common stock for cash upon exercise of stock options (in shares)				159,576
Issuance of common stock for cash upon exercise of stock options	1,647						1,647
Issuance of common stock for cash upon exercise of warrants (in shares)				34,567
Issuance of common stock for cash upon exercise of warrants	1,109						1,109
Employee stock-based compensation expense	6,653						6,653
Foreign currency translation adjustment	962									962
Net loss	(2,818)										(2,818)
Ending balance (in shares) at Sep. 30, 2020				49,132,348
Ending balance at Sep. 30, 2020	268,644			$ 47			621,961			(4,352)	(349,012)
Beginning balance (in shares) at Dec. 31, 2020				49,441,166
Beginning balance at Dec. 31, 2020	277,679			$ 49			632,253			(2,096)	(352,527)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common shares, net of commissions and offering costs (in shares)					2,211,538
Issuance of common shares, net of commissions and offering costs		$ 188,755			$ 2			$ 188,753
Issuance of common stock under ESPP (in shares)				24,052
Issuance of common stock under ESPP	838						838
RSU settlements, net of shares withheld (in shares)				121,447
RSU settlements, net of shares withheld	(2,313)						(2,313)
Issuance of common stock for services (in shares)				1,339
Issuance of common stock for services	96						96
Issuance of common stock for cash upon exercise of stock options (in shares)				139,579
Issuance of common stock for cash upon exercise of stock options	2,193						2,193
Employee stock-based compensation expense	6,488						6,488
Foreign currency translation adjustment	(1,503)									(1,503)
Net loss	(687)										(687)
Ending balance (in shares) at Mar. 31, 2021				51,939,121
Ending balance at Mar. 31, 2021	471,546			$ 51			828,308			(3,599)	(353,214)
Beginning balance (in shares) at Dec. 31, 2020				49,441,166
Beginning balance at Dec. 31, 2020	277,679			$ 49			632,253			(2,096)	(352,527)
Ending balance (in shares) at Jun. 30, 2021				52,552,761
Ending balance at Jun. 30, 2021	479,843			$ 51			838,089			(3,156)	(355,141)
Beginning balance (in shares) at Dec. 31, 2020				49,441,166
Beginning balance at Dec. 31, 2020	$ 277,679			$ 49			632,253			(2,096)	(352,527)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock for cash upon exercise of stock options (in shares)	646,724
Foreign currency translation adjustment	$ (1,997)
Net loss	(14,511)
Ending balance (in shares) at Sep. 30, 2021				52,776,733
Ending balance at Sep. 30, 2021	472,147			$ 52			843,226			(4,093)	(367,038)
Beginning balance (in shares) at Mar. 31, 2021				51,939,121
Beginning balance at Mar. 31, 2021	471,546			$ 51			828,308			(3,599)	(353,214)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
RSU settlements, net of shares withheld (in shares)				160,286
RSU settlements, net of shares withheld	(6,638)						(6,638)
Issuance of common stock for services (in shares)				23,163
Issuance of common stock for services	59						59
Issuance of common stock for cash upon exercise of stock options (in shares)				427,059
Issuance of common stock for cash upon exercise of stock options	6,833						6,833
Issuance of common stock for cash upon exercise of warrants (in shares)				3,132
Issuance of common stock for cash upon exercise of warrants	205						205
Employee stock-based compensation expense	9,322						9,322
Foreign currency translation adjustment	443									443
Net loss	(1,927)										(1,927)
Ending balance (in shares) at Jun. 30, 2021				52,552,761
Ending balance at Jun. 30, 2021	479,843			$ 51			838,089			(3,156)	(355,141)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock under ESPP (in shares)				21,412
Issuance of common stock under ESPP	1,301						1,301
RSU settlements, net of shares withheld (in shares)				118,466
RSU settlements, net of shares withheld	(8,707)						(8,707)
Issuance of common stock for services (in shares)				4,008
Issuance of common stock for services	75						75
Issuance of common stock for cash upon exercise of stock options (in shares)				80,086
Issuance of common stock for cash upon exercise of stock options	1,895			$ 1			1,894
Employee stock-based compensation expense	10,574						10,574
Foreign currency translation adjustment	(937)									(937)
Net loss	(11,897)										(11,897)
Ending balance (in shares) at Sep. 30, 2021				52,776,733
Ending balance at Sep. 30, 2021	$ 472,147			$ 52			$ 843,226			$ (4,093)	$ (367,038)