Summary of Significant Accounting Policies - Loss Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Numerator:
Net loss (basic and diluted)	$ (5,786)	$ (7,587)	$ (16,510)	$ (24,033)
Denominator:
Weighted-average shares of common stock (basic and diluted)	8,923,374	8,694,104	8,922,052	8,304,510
Basic and diluted net loss per share	$ (0.65)	$ (0.87)	$ (1.85)	$ (2.89)
Potentially dilutive securities excluded from computation of diluted net loss per share			3,277,300	3,148,491
Options
Denominator:
Potentially dilutive securities excluded from computation of diluted net loss per share			1,543,978	1,415,169
Warrants | Common Stock
Denominator:
Potentially dilutive securities excluded from computation of diluted net loss per share			1,733,322	1,733,322