Net Loss per Share - Basic and Diluted Net Loss per Share (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024
Numerator:
Net loss attributable to common stockholder—basic	$ (37.5)	$ (67.7)	$ (143.8)	$ (172.2)
Net loss attributable to common stockholders—diluted	$ (37.5)	$ (67.7)	$ (143.8)	$ (172.2)
Denominator:
Weighted average common shares outstanding—basic (in shares)	74,194,138	71,138,070	73,520,889	70,716,140
Weighted average common shares outstanding—diluted (in shares)	74,194,138	71,138,070	73,520,889	70,716,140
Net loss per share attributable to common stockholders—basic (usd per share)	$ (0.51)	$ (0.95)	$ (1.96)	$ (2.44)
Net loss per share attributable to common stockholders—diluted (usd per share)	$ (0.51)	$ (0.95)	$ (1.96)	$ (2.44)