Pension - Components of Net Periodic Benefit Cost (Details) - Pension Benefits - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 0.5	$ 0.4
Interest cost	2.3	2.6
Expected return on plan assets	(3.3)	(3.8)
Amortization of net actuarial losses	2.0	1.7
Net periodic cost	$ 1.5	$ 0.9