Convertible Preferred Stock and Preferred Stock Warrants - Schedule (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Temporary Equity [Line Items]
Convertible preferred stock, authorized (shares)	0	31,557,107
Convertible preferred stock, issued (shares)	0	31,557,107
Convertible preferred stock, outstanding (shares)	0	31,557,107	24,445,555	15,671,730
Convertible preferred stock, carrying value	$ 0.0	$ 480.2	$ 180.8	$ 60.4
Convertible preferred stock, liquidation preference	$ 0.0	$ 480.8
Convertible preferred stock, common stock issuable upon conversion (shares)		31,557,107
Series Seed Preferred stock
Temporary Equity [Line Items]
Convertible preferred stock, authorized (shares)		7,905,140
Convertible preferred stock, issued (shares)		7,905,140
Convertible preferred stock, outstanding (shares)		7,905,140
Convertible preferred stock, carrying value		$ 12.9
Convertible preferred stock, liquidation preference		$ 13.0
Convertible preferred stock, common stock issuable upon conversion (shares)		7,905,140
Series A Preferred stock
Temporary Equity [Line Items]
Convertible preferred stock, authorized (shares)		3,328,774
Convertible preferred stock, issued (shares)		3,328,774
Convertible preferred stock, outstanding (shares)		3,328,774
Convertible preferred stock, carrying value		$ 14.0
Convertible preferred stock, liquidation preference		$ 13.6
Convertible preferred stock, common stock issuable upon conversion (shares)		3,328,774
Series B Preferred stock
Temporary Equity [Line Items]
Convertible preferred stock, authorized (shares)		4,511,417
Convertible preferred stock, issued (shares)		4,511,417
Convertible preferred stock, outstanding (shares)		4,511,417
Convertible preferred stock, carrying value		$ 34.1
Convertible preferred stock, liquidation preference		$ 34.1
Convertible preferred stock, common stock issuable upon conversion (shares)		4,511,417
Series C Preferred Stock
Temporary Equity [Line Items]
Convertible preferred stock, authorized (shares)		8,703,846
Convertible preferred stock, issued (shares)		8,703,846
Convertible preferred stock, outstanding (shares)		8,703,846
Convertible preferred stock, carrying value		$ 119.8
Convertible preferred stock, liquidation preference		$ 120.1
Convertible preferred stock, common stock issuable upon conversion (shares)		8,703,846
Series D Preferred Stock
Temporary Equity [Line Items]
Convertible preferred stock, authorized (shares)		7,107,930
Convertible preferred stock, issued (shares)		7,107,930
Convertible preferred stock, outstanding (shares)		7,107,930
Convertible preferred stock, carrying value		$ 299.4
Convertible preferred stock, liquidation preference		$ 300.0
Convertible preferred stock, common stock issuable upon conversion (shares)		7,107,930