Pension - Components of Net Periodic Benefit Cost (Details) - Pension Benefits - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 0.6	$ 0.5	$ 1.1	$ 0.9
Interest cost	2.3	2.9	4.6	5.5
Expected return on plan assets	(3.3)	(3.8)	(6.6)	(7.6)
Amortization of net actuarial losses	2.0	1.4	4.0	3.1
Net periodic cost	$ 1.6	$ 1.0	$ 3.1	$ 1.9