Net Loss Per Share (Tables)

9 Months Ended

Sep. 30, 2019

401(k) Plan

Schedule of Earnings Per Share, Basic and Diluted [Table Text Block]

	Three Months Ended September 30,				Nine Months Ended September 30,
	2019		2018		2019		2018
Convertible preferred stock (as converted)		—		17,248,259		—		17,248,259
Common stock options		3,690,398		1,638,380		3,690,398		1,638,380
Common stock warrants		49,997		62,936		49,997		62,936
Convertible preferred stock warrants		—		49,997		—		49,997
Early exercised stock options		2,284		—		2,284		—
		3,742,679		18,999,572		3,742,679		18,999,572