Earnings (loss) per common share - Schedule of Basic and Diluted Net Loss per Share (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended						9 Months Ended
	Sep. 30, 2025	Jun. 30, 2025	Mar. 31, 2025	Sep. 30, 2024	Jun. 30, 2024	Mar. 31, 2024	Sep. 30, 2025	Sep. 30, 2024
Numerator:
Net income (loss)	$ 51.2	$ (12.0)	$ 68.0	$ 114.8	$ (283.1)	$ 9.0	$ 107.2	$ (159.3)
Denominator:
Weighted-average number of shares outstanding-basic (in shares)	53.2			53.1			53.9	52.6
Dilutive securities - equity awards (in shares)	3.3			2.5			2.8	0.0
Weighted-average number of shares outstanding-diluted (in shares)	56.5			55.6			56.7	52.6
Earnings (loss) per common share - basic - basic (in dollars per share)	$ 0.96			$ 2.16			$ 1.99	$ (3.03)
Earnings (loss) per common share - basic - diluted (in dollars per share)	$ 0.91			$ 2.06			$ 1.89	$ (3.03)
Anti-dilutive securities (in shares)	5.0			2.6			4.7	4.4