CONDENSED CONSOLIDATED STATEMENTS OF STOCKHOLDERS' DEFICIT (Unaudited) - USD ($) shares in Millions, $ in Millions	Total	Common Stock	Additional Paid-In Capital	Accumulated Other Comprehensive Income	Accumulated Deficit	Treasury Stock, at Cost
Beginning balance (in shares) at Dec. 31, 2023		220.5
Beginning balance at Dec. 31, 2023	$ (154.5)	$ 2.2	$ 2,638.2	$ 60.3	$ (2,824.2)	$ (31.0)
Beginning balance (in shares) at Dec. 31, 2023						3.1
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Exercise of stock options and release of stock awards, net of shares withheld (in shares)		6.1
Exercise of stock options and release of stock awards, net of shares withheld	(3.4)	$ 0.1	(3.5)
Share-based compensation expense for equity classified awards	13.0		13.0
Net loss	(640.6)				(640.6)
Other comprehensive loss	(1.7)			(1.7)
Ending balance (in shares) at Mar. 31, 2024		226.6
Ending balance at Mar. 31, 2024	$ (787.2)	$ 2.3	2,647.7	58.6	(3,464.8)	$ (31.0)
Ending balance (in shares) at Mar. 31, 2024						3.1
Beginning balance (in shares) at Dec. 31, 2024	229.1	232.2
Beginning balance at Dec. 31, 2024	$ (1,004.2)	$ 2.3	2,682.8	24.1	(3,682.4)	$ (31.0)
Beginning balance (in shares) at Dec. 31, 2024	3.1					3.1
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Exercise of stock options and release of stock awards, net of shares withheld (in shares)		8.2
Exercise of stock options and release of stock awards, net of shares withheld	$ 0.0	$ 0.1	(0.1)
Share-based compensation expense for equity classified awards	7.6		7.6
Net loss	(71.5)				(71.5)
Other comprehensive loss	$ (5.0)			(5.0)
Ending balance (in shares) at Mar. 31, 2025	237.3	240.4
Ending balance at Mar. 31, 2025	$ (1,073.1)	$ 2.4	$ 2,690.3	$ 19.1	$ (3,753.9)	$ (31.0)
Ending balance (in shares) at Mar. 31, 2025	3.1					3.1