Net Loss Per Share (Details) - shares	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive securities not included in the diluted net loss per share calculation	3,742,679	18,999,572	3,742,679	18,999,572
Convertible preferred stock (as converted)
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive securities not included in the diluted net loss per share calculation		17,248,259		17,248,259
Common stock options
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive securities not included in the diluted net loss per share calculation	3,690,398	1,638,380	3,690,398	1,638,380
Common stock warrants
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive securities not included in the diluted net loss per share calculation	49,997	62,936	49,997	62,936
Convertible preferred stock warrants
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive securities not included in the diluted net loss per share calculation		49,997		49,997
Early exercised stock options
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive securities not included in the diluted net loss per share calculation	2,284		2,284