Pensions - Components of Net Pension Income (Details) - Pension Plan - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 0.3	$ 0.4	$ 0.7	$ 0.8
Interest cost	3.7	3.6	7.3	7.2
Expected return on plan assets	(5.3)	(12.0)	(10.7)	(24.0)
Amortization of unrecognized loss	5.1	5.2	10.2	10.4
Amortization of prior service cost	(0.1)	(0.1)	(0.2)	(0.2)
Defined benefit plan expense (income)	$ 3.7	$ (2.9)	$ 7.3	$ (5.8)