Pension Benefits and Postretirement Benefits Other Than Pensions (Details) $ in Millions	3 Months Ended
	Mar. 31, 2017 USD ($) employees	Mar. 31, 2016 USD ($)
Pension Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Pension Plan, Number of Participants and Beneficiaries | employees	9,200
Defined Benefit Pension Plans, Number of Active Employees | employees	1,800
Service Cost Earned	$ 0.0	$ 2.2
Interest Cost on Projected Benefit Obligation	5.1	5.4
Expected Return on Plan Assets	(7.7)	(8.2)
Amortization of Accumulated Net Unrecognized Pension Costs	0.6	3.0
Total Expense (Benefit) Recognized	$ (2.0)	2.4
Postretirement Benefits Other than Pensions [Member]
Defined Benefit Plan Disclosure [Line Items]
Other Postretirement Benefit Plan, Number of Retired Employees Covered | employees	500
Other Postretirement Benefit Plan, Number of Active Employees Covered | employees	225
Service Cost Earned	$ 0.0	0.0
Interest Cost on Projected Benefit Obligation	0.1	0.2
Amortization of Prior Service Credit	(0.3)	0.0
Amortization of Accumulated Net Unrecognized Pension Costs	(0.4)	(0.3)
Total Expense (Benefit) Recognized	$ (0.6)	$ (0.1)