Condensed Balance Sheets (Parenthetical) - $ / shares	Jun. 30, 2020	Dec. 31, 2019
Statement Of Financial Position [Abstract]
Convertible preferred stock, par value	$ 0.0001	$ 0.0001
Convertible preferred stock, authorized	0	38,055,000
Convertible preferred stock, issued	0	37,267,000
Convertible preferred stock, outstanding	0	37,267,000
Preferred stock, par value	$ 0.0001	$ 0.0001
Preferred stock, shares authorized	40,000,000	0
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value	$ 0.0001	$ 0.0001
Common stock, shares authorized	400,000,000	52,042,000
Common stock, shares issued	37,527,000	2,989,000
Common stock, shares outstanding	37,527,000	2,989,000