Condensed Balance Sheets (Parenthetical) (Unaudited) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Preferred stock, par value	$ 0.001	$ 0.001
Preferred stock, shares authorized	10,000,000	0
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value	$ 0.001	$ 0.001
Common stock, shares authorized	100,000,000	24,794,114
Common stock, shares issued	26,841,149	3,412,366
Common stock, shares outstanding	26,841,149	3,412,366
Series A Redeemable Convertible Preferred Stock
Redeemable convertible preferred stock, par value	$ 0.001	$ 0.001
Redeemable convertible preferred stock, shares authorized	0	9,008,931
Redeemable convertible preferred stock, shares issued	0	9,008,919
Redeemable convertible preferred stock, shares outstanding	0	9,008,919
Redeemable convertible preferred stock, liquidation preference	$ 0	$ 17,178
Series B Redeemable Convertible Preferred Stock
Redeemable convertible preferred stock, par value	$ 0.001	$ 0.001
Redeemable convertible preferred stock, shares authorized	0	9,430,145
Redeemable convertible preferred stock, shares issued	0	9,152,108
Redeemable convertible preferred stock, shares outstanding	0	9,152,108
Redeemable convertible preferred stock, liquidation preference	$ 0	$ 87,972