Earnings (Loss) per Share - Earnings per share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Millions	3 Months Ended				6 Months Ended
	Jun. 30, 2025	Mar. 31, 2025	Jun. 30, 2024	Mar. 31, 2024	Jun. 30, 2025	Jun. 30, 2024
Earnings Per Share Reconciliation
Net income (loss)	$ (146.5)	$ 20.5	$ (283.7)	$ (56.0)	$ (126.0)	$ (339.7)
Basic and Diluted earnings (loss) per share
Basic earnings (loss) per share (usd per share)	$ (4.02)		$ (7.81)		$ (3.46)	$ (9.36)
Diluted earnings (loss) per share (usd per share)	$ (4.02)		$ (7.81)		$ (3.46)	$ (9.36)
Shares (in thousands)
Weighted average number of common shares outstanding - Basic (shares)	36,461		36,335		36,422	36,299
Weighted average additional shares assuming conversion of potential common shares (shares)	0		0		0	0
Shares - diluted basis (shares)	36,461		36,335		36,422	36,299