Pension and Other Postretirement Benefits (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Defined Benefit Pension [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service cost	$ 1.7	$ 1.4	$ 3.3	$ 3.0
Interest cost	3.9	4.0	7.7	7.9
Expected return on plan assets	6.0	6.5	12.0	13.0
Defined Benefit Plan, Settlements, Benefit Obligation	0.1		0.1
Unrecognized prior service credit	0.0	(0.3)	0.0	(0.5)
Unrecognized net actuarial loss (gain)	(2.4)	(2.5)	(4.7)	(5.1)
Net expense	2.1	1.1	3.8	2.5
Other Postretirement Benefit Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service cost	0.1	0.1	0.1	0.1
Interest cost	0.3	0.2	0.5	0.5
Expected return on plan assets	0.0	0.0	0.0	0.0
Unrecognized prior service credit	(0.1)	0.0	(0.1)	(0.1)
Unrecognized net actuarial loss (gain)	0.1	0.2	0.2	0.2
Net expense	$ 0.2	$ 0.1	$ 0.3	$ 0.3