Pension Benefits - Components Of Comprehensive Pension Expense (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Defined Benefit Plan Disclosure [Line Items]
Unrecognized Pension Loss (Gain) Arising During the Year	$ (14.2)	$ (3.0)	$ 106.4
Amortization of Accumulated Unrecognized Pension Loss	(5.3)	(23.1)	(7.9)
Pension Plans, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Service Cost Earned During the Year	4.8	10.5	8.7
Interest Cost on Projected Benefit Obligation	20.1	25.7	24.8
Expected Return on Plan Assets	(32.7)	(35.0)	(34.9)
Amortization of Actuarial Loss	6.6	24.4	9.7
Curtailment Gain	(0.3)	0.0	0.0
Pension Expense (Income) Recognized in Consolidated Statements of Income	(1.5)	25.6	8.3
Unrecognized Pension Loss (Gain) Arising During the Year	(0.7)	(1.9)	102.0
Prior Service Credit Arising During the Year	0.0	0.0	(0.6)
Amortization of Accumulated Unrecognized Pension Loss	(6.3)	(24.4)	(9.7)
Comprehensive Pension Expense (Income)	(8.5)	$ (0.7)	$ 100.0
Amounts that will be amortized from AOCI in next Fiscal Year	$ 2.5