Retirement Plans - Components of Net Periodic Benefit Cost (Credit) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Defined Benefit Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 3.8	$ 5.1
Interest cost	5.2	2.3
Expected return on assets	(4.6)	(3.9)
Net (gain) loss	(0.9)	0.5
Prior service cost (credit)	0.2	0.2
Total benefit cost (credit)	3.7	4.2
Retiree Health Care Plan
Defined Benefit Plan Disclosure [Line Items]
Service cost	0.0	0.0
Interest cost	0.1	0.1
Expected return on assets	0.0	0.0
Net (gain) loss	0.0	0.0
Prior service cost (credit)	(0.2)	(0.2)
Total benefit cost (credit)	$ (0.1)	$ (0.1)