CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Redeemable convertible preferred stock, par value (in dollars per share)	$ 0.0001	$ 0.0001
Redeemable convertible preferred stock, authorized	0	1,323,506
Redeemable convertible preferred stock, shares issued	0	1,323,506
Redeemable convertible preferred stock, shares outstanding	0	1,323,506
Preferred stock, aggregate liquidation preference	$ 0.0	$ 99.7
Common stock
Common stock, par value (in dollars per share)	$ 0.0001	$ 0.0001
Common stock, shares authorized	100,000,000	18,454,860
Common stock, shares issued	21,746,392	1,006,595
Common stock, shares outstanding	21,746,392	1,006,595
Class A common stock
Common stock, par value (in dollars per share)	$ 0.0001	$ 0.0001
Common stock, shares authorized	3,900,000	0
Common stock, shares issued	3,819,732	0
Common stock, shares outstanding	3,819,732	0