Net Loss Per Share - Reconciliation (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Numerator:
Net loss attributable to common stockholders - basic	$ (241.3)	$ (122.3)	$ (108.5)
Net loss attributable to common stockholders - diluted	$ (241.3)	$ (122.3)	$ (108.5)
Denominator:
Weighted average common shares outstanding - basic (shares)	61,224,433	33,654,828	11,124,397
Weighted average common shares outstanding - diluted (shares)	61,224,433	33,654,828	11,124,397
Net loss per share attributable to common stockholders - basic (usd per share)	$ (3.94)	$ (3.63)	$ (9.75)
Net loss per share attributable to common stockholders - diluted (usd per share)	$ (3.94)	$ (3.63)	$ (9.75)