Loss per share - Schedule of EPS (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items]
Total net income (loss)	$ (8.2)	$ (32.0)	$ (144.9)	$ (68.3)
Weighted average number of common shares (in shares)	22.5	22.1	22.5	22.1
Effect of dilutive securities:
Dilutive number of shares (in shares)	22.5	22.1	22.5	22.1
Diluted earnings (loss) per share (in dollars per share)	$ (0.36)	$ (1.45)	$ (6.44)	$ (3.08)
Basic earnings (loss) per share (in dollars per share)	$ (0.36)	$ (1.45)	$ (6.44)	$ (3.08)
Stock options
Effect of dilutive securities:
Effect of dilutive securities, Stock options and Restricted share units (in shares)	0.0	0.0	0.0	0.0
Restricted share units
Effect of dilutive securities:
Effect of dilutive securities, Stock options and Restricted share units (in shares)	0.0	0.0	0.0	0.0