Goodwill and intangible assets - Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Goodwill [Line Items]
Goodwill	$ 287.4	$ 287.1	$ 315.0
Amortization expense	9.7	10.1	3.0
Other
Goodwill [Line Items]
Goodwill	$ 10.3	$ 10.3	$ 10.3