Consolidated Statements of Comprehensive Income - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Statement of Comprehensive Income [Abstract]
Net income	$ 139.1	$ 133.0	$ 93.1
Changes in cumulative translation adjustment	18.3	(34.7)	(22.2)
Amortization of prior service cost/(credit)	0.5	0.5	0.3
Amortization of actuarial net losses/(gains)	(2.1)	0.5	2.6
Actuarial net gains/(losses) arising during the year	(23.4)	(93.9)	37.2
Other comprehensive income, before tax	132.4	5.4	111.0
Income tax income/(expense) related to other comprehensive income	3.8	29.3	(7.5)
Total comprehensive income	$ 136.2	$ 34.7	$ 103.5