Pension - Components of Net Periodic Benefit Cost (Details) - Pension Benefits - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 0.7	$ 0.4	$ 1.8	$ 1.3
Interest cost	2.3	2.9	6.9	8.4
Expected return on plan assets	(3.3)	(3.8)	(9.9)	(11.4)
Amortization of net actuarial losses	2.1	1.4	6.1	4.5
Net periodic cost	$ 1.8	$ 0.9	$ 4.9	$ 2.8