Net Loss Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Numerator [Abstract]
Net loss attributable to common stockholders	$ (34,525)	$ (25,040)	$ (74,704)	$ (49,704)
Denominator [Abstract]
Weighted-average common shares outstanding - basic (in shares)	63,061,232	55,158,459	62,321,926	55,020,789
Weighted-average common shares outstanding - diluted (in shares)	63,061,232	55,158,459	62,321,926	55,020,789
Net loss per share attributable to common stockholders - basic (in dollars per share)	$ (0.55)	$ (0.45)	$ (1.20)	$ (0.90)
Net loss per share attributable to common stockholders - diluted (in dollars per share)	$ (0.55)	$ (0.45)	$ (1.20)	$ (0.90)
Weighted Average Number of Shares Outstanding Reconciliation [Abstract]
Warrants exercisable for common shares (in shares)	610,437	14,102	610,437	14,102
Restricted stock units exercisable for common shares (in shares)	23,500	0	23,500	0
Options to purchase common shares (in shares)	11,040,697	10,776,813	11,040,697	10,776,813
Weighted average number diluted shares outstanding (in shares)	11,835,170	12,411,863	11,835,170	12,411,863
Convertible Notes 2021 [Member]
Weighted Average Number of Shares Outstanding Reconciliation [Abstract]
Shares issuable upon conversion of Convertible Notes (in shares)	160,536	160,536	160,536	160,536
Convertible Notes 2022 [Member]
Weighted Average Number of Shares Outstanding Reconciliation [Abstract]
Shares issuable upon conversion of Convertible Notes (in shares)	0	1,460,412	0	1,460,412