Post Retirement Benefit Plans - Changes in Benefit Obligations and Plan Assets (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Change in benefit obligation:
Benefit obligation at beginning of year	$ 197.8	$ 253.9
Service cost	5.5	6.5	$ 8.1
Interest cost	5.2	1.0	0.5
Plan participant contributions	6.4	5.1
Plan amendments	(2.4)	(2.9)
Plan settlements	0.0	(6.8)
Benefits paid	(6.8)	(2.1)
Actuarial gain	27.5	(48.8)
Premiums paid	(2.3)	(1.7)
Plan combinations / acquisitions	6.1	0.8
Impact of foreign currency exchange rates	19.1	(7.2)
Benefit obligation at end of year	256.1	197.8	253.9
Change in plan assets:
Fair value of plan assets at beginning of year	150.3	147.8
Return on plan assets	1.5	2.5
Plan participant and employer contributions	14.4	11.9
Benefits paid	(6.8)	(2.1)
Plan settlements	0.0	(6.8)
Premiums paid	(2.3)	(1.7)
Plan combinations / acquisitions	4.8	0.4
Impact of foreign currency exchange rates	15.5	(1.7)
Fair value of plan assets at end of year	177.4	150.3	$ 147.8
Net under funded status	(78.7)	(47.5)
Accumulated benefit obligation	$ 226.4	$ 168.6