Pension Plans (Components of Net Periodic Benefit Cost) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Compensation And Retirement Disclosure [Abstract]
Interest cost	$ 19.8	$ 21.9	$ 24.9
Expected return on plan assets	(20.6)	(21.4)	(23.5)
Recognized net actuarial loss	9.6	13.5	11.2
Net periodic pension cost (benefit)	$ 8.8	$ 14.0	$ 12.6