Pension and Other Post-Retirement Benefits (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Defined Benefit Pension [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 1.7	$ 1.4
Interest cost	4.9	5.1
Expected return on plan assets	(6.5)	(7.2)
Unrecognized prior service credit	(0.2)	(0.2)
Unrecognized net actuarial loss	3.5	2.6
Net expense	3.4	1.7
Retiree Health and Life [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	0	0
Interest cost	0.4	0.4
Expected return on plan assets	0	0
Unrecognized prior service credit	0	0
Unrecognized net actuarial loss	0	0
Net expense	$ 0.4	$ 0.4