Pension Plans (Components of Net Periodic Pension (Benefit) Cost) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Compensation And Retirement Disclosure [Abstract]
Defined Benefit Plan, Type [Extensible List]	us-gaap:PensionPlansDefinedBenefitMember	us-gaap:PensionPlansDefinedBenefitMember
Interest cost	$ 3.7	$ 4.6
Expected return on plan assets	(4.6)	(5.6)
Recognized net actuarial loss	0.8	1.5
Net periodic pension (benefit) cost	$ (0.1)	$ 0.5