Pension and Other Postretirement Benefit Plans (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Pension Plans [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service cost - benefits earned during the period		$ 0.2		$ 0.6
Interest cost	$ 6.4	7.4	$ 19.3	22.2
Expected return on plan assets	(6.8)	(7.4)	(20.4)	(22.4)
Recognized net actuarial loss	3.8	2.8	11.4	8.4
Net periodic pension cost (benefit)	3.4	3.0	10.3	8.8
Postretirement Plans [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Interest cost	0.1	0.2	0.3	0.4
Recognized net actuarial loss			0.1	0.1
Amortization of prior service cost	(0.3)	(0.3)	(1.0)	(1.0)
Net periodic pension cost (benefit)	$ (0.2)	$ (0.1)	$ (0.6)	$ (0.5)