Pension and Other Postretirement Benefit Plans (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Pension Plans [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Interest cost	$ 5.0	$ 5.4	$ 14.9	$ 16.4
Expected return on plan assets	(5.2)	(5.3)	(15.5)	(16.1)
Recognized net actuarial loss	2.4	3.4	7.2	10.2
Net periodic pension cost (benefit)	2.2	3.5	6.6	10.5
Postretirement Plans [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Interest cost	0.1	0.1	0.3	0.3
Recognized net actuarial loss			0.1	0.1
Amortization of prior service cost		(0.3)	(0.2)	(1.0)
Net periodic pension cost (benefit)	$ 0.1	$ (0.2)	$ 0.2	$ (0.6)