Net Loss per Share - Reconciliation (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Numerator:
Net loss attributable to common stockholder—basic	$ (61.5)	$ (91.4)	$ (194.5)	$ (234.1)
Net loss attributable to common stockholders—diluted	$ (61.5)	$ (91.4)	$ (194.5)	$ (234.1)
Denominator:
Weighted average common shares outstanding—basic (in shares)	69,753,576	66,877,100	69,542,342	63,482,945
Weighted average common shares outstanding—diluted (in shares)	69,753,576	66,877,100	69,542,342	63,482,945
Net loss per share attributable to common stockholders—basic (usd per share)	$ (0.88)	$ (1.37)	$ (2.80)	$ (3.69)
Net loss per share attributable to common stockholders—diluted (usd per share)	$ (0.88)	$ (1.37)	$ (2.80)	$ (3.69)