Common stock and additional paid-in capital - Schedule of Stockholders' Equity (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance, common shares, outstanding (in shares)			22,200,000
Beginning balance, equity	$ 235.7	$ 439.9	$ 376.4	$ 501.6
Issuance of common stock in connection with the ATM Program	1.2		1.2
Stock-based compensation - RSUs	3.0	3.0	6.1	8.5
Stock-based compensation - options	$ (1.1)	1.0	$ 0.0	2.8
Ending balance, common shares, outstanding (in shares)	23,200,000		23,200,000
Ending balance, equity	$ 295.3	$ 413.2	$ 295.3	$ 413.2
Number of common shares
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance, common shares, outstanding (in shares)	22,500,000	22,225,000	22,200,000	22,012,500
Settlement of RSUs (in shares)	0	37,500	300,000	100,000
Issuance of common stock in connection with the ATM Program (in shares)	700,000		700,000
Ending balance, common shares, outstanding (in shares)	23,200,000	22,275,000	23,200,000	22,275,000
Common stock and additional paid-in capital
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance, equity	$ 652.5	$ 642.2	$ 648.3	$ 635.3
Issuance of common stock in connection with the ATM Program	1.2		1.2
Stock-based compensation - RSUs	3.0	3.0	6.1	8.5
Stock-based compensation - options	(1.1)	1.0	0.0	2.8
Ending balance, equity	$ 655.6	$ 646.2	$ 655.6	$ 646.2