CONDENSED CONSOLIDATED STATEMENTS OF REDEEMABLE CONVERTIBLE PREFERRED STOCK AND STOCKHOLDERS’ EQUITY - UNAUDITED - USD ($) shares in Millions, $ in Millions	Total	Class A Shares	Class B Shares	Class A and Class B Convertible Common Stock	Class A and Class B Convertible Common Stock Class A Shares	Class A and Class B Convertible Common Stock Class B Shares	Additional Paid-in Capital	Accumulated Other Comprehensive (Loss) Income	Accumulated Loss
Beginning balance (in shares) at Dec. 31, 2022	14.1
Beginning balance at Dec. 31, 2022	$ 112.0
Ending balance (in shares) at Sep. 30, 2023	14.1
Ending balance at Sep. 30, 2023	$ 112.0
Beginning balance (in shares) at Dec. 31, 2022					9.2	5.0
Beginning balance at Dec. 31, 2022	277.1			$ 0.0			$ 1,850.7	$ (5.8)	$ (1,567.8)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	(123.4)								(123.4)
Other comprehensive income (loss)	(0.8)							(0.8)
Common stock—option exercises and restricted stock units vesting, net of shares withheld for employee taxes (in shares)					0.3
Common stock—share-based compensation expense	12.4						12.4
Warrant compensation expense	13.3						13.3
Warrant issuance costs	(1.5)						(1.5)
Ending balance (in shares) at Sep. 30, 2023					9.5	5.0
Ending balance at Sep. 30, 2023	$ 177.1			0.0			1,874.9	(6.6)	(1,691.2)
Beginning balance (in shares) at Jun. 30, 2023	14.1
Beginning balance at Jun. 30, 2023	$ 112.0
Ending balance (in shares) at Sep. 30, 2023	14.1
Ending balance at Sep. 30, 2023	$ 112.0
Beginning balance (in shares) at Jun. 30, 2023					9.4	5.0
Beginning balance at Jun. 30, 2023	214.4			0.0			1,865.7	(5.9)	(1,645.4)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	(45.8)								(45.8)
Other comprehensive income (loss)	(0.7)							(0.7)
Common stock—option exercises and restricted stock units vesting, net of shares withheld for employee taxes (in shares)					0.1
Common stock—share-based compensation expense	4.7						4.7
Warrant compensation expense	5.0						5.0
Warrant issuance costs	(0.5)						(0.5)
Ending balance (in shares) at Sep. 30, 2023					9.5	5.0
Ending balance at Sep. 30, 2023	$ 177.1			0.0			1,874.9	(6.6)	(1,691.2)
Beginning balance (in shares) at Dec. 31, 2023	14.1
Beginning balance at Dec. 31, 2023	$ 112.0
Ending balance (in shares) at Sep. 30, 2024	14.1
Ending balance at Sep. 30, 2024	$ 112.0
Beginning balance (in shares) at Dec. 31, 2023		9.5	5.0		9.5	5.0
Beginning balance at Dec. 31, 2023	165.7			0.0			1,883.4	(2.5)	(1,715.2)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	8.8								8.8
Other comprehensive income (loss)	$ 4.6							4.6
Conversion of Class B to Class A (in shares)					0.6	(0.6)
Common stock—option exercises and restricted stock units vesting, net of shares withheld for employee taxes (in shares)	0.0				0.5
Common stock—restricted stock units vesting, net of shares withheld for employee taxes	$ (13.3)						(15.7)		2.4
Common stock—share-based compensation expense	12.7						12.7
Warrant compensation expense	3.8						3.8
Warrant issuance costs	(0.4)						(0.4)
Ending balance (in shares) at Sep. 30, 2024		10.6	4.4		10.6	4.4
Ending balance at Sep. 30, 2024	$ 181.9			0.0			1,883.8	2.1	(1,704.0)
Beginning balance (in shares) at Jun. 30, 2024	14.1
Beginning balance at Jun. 30, 2024	$ 112.0
Ending balance (in shares) at Sep. 30, 2024	14.1
Ending balance at Sep. 30, 2024	$ 112.0
Beginning balance (in shares) at Jun. 30, 2024					10.6	4.4
Beginning balance at Jun. 30, 2024	151.3			0.0			1,881.5	(3.4)	(1,726.8)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	22.8								22.8
Other comprehensive income (loss)	5.5							5.5
Common stock—restricted stock units vesting, net of shares withheld for employee taxes	(2.0)						(2.0)
Common stock—share-based compensation expense	4.3						4.3
Ending balance (in shares) at Sep. 30, 2024		10.6	4.4		10.6	4.4
Ending balance at Sep. 30, 2024	$ 181.9			$ 0.0			$ 1,883.8	$ 2.1	$ (1,704.0)