Balance Sheets (Unaudited) (Parenthetical) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Statement Of Financial Position [Abstract]
Accounts payable, related parties	$ 331	$ 200
Accrued expenses, related parties	$ 415	$ 308
Common stock, par value	$ 0.0001	$ 0.0001
Common stock, authorized shares	400,000,000	400,000,000
Common stock, issued shares	28,964,506	28,964,506
Common stock, outstanding shares	25,916,093	24,728,258