Net Loss Per Share - Schedule of Antidilutive Securities, Excluded from Computation of Diluted Net Loss per Share (Details) - shares	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Antidilutive Securities Excluded from Computation of Earnings Per Share
Total common stock equivalents	13,708,588	5,249,770	4,021,313
Options to Purchase Common Stock
Antidilutive Securities Excluded from Computation of Earnings Per Share
Total common stock equivalents	7,920,417	5,230,831	4,002,374
2026 Convertible Notes
Antidilutive Securities Excluded from Computation of Earnings Per Share
Total common stock equivalents	5,769,232
Warrant | Common Stock
Antidilutive Securities Excluded from Computation of Earnings Per Share
Total common stock equivalents	18,939	18,939	18,939