Pension Benefits - Components Of Comprehensive Pension Expense (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Defined Benefit Plan Disclosure [Line Items]
Unrecognized Pension Gain (Loss) Arising During the Year	$ 8.0	$ (3.9)	$ (14.2)
Amortization of Accumulated Unrecognized Pension Loss	(1.1)	0.6	(5.3)
Pension Plans, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Service Cost Earned During the Year	0.0	0.0	4.8
Interest Cost on Projected Benefit Obligation	20.3	20.6	20.1
Expected Return on Plan Assets	(28.9)	(30.9)	(32.7)
Amortization of Actuarial Loss	4.3	2.6	6.6
Curtailment Gain	0.0	0.0	(0.3)
Pension Expense (Income) Recognized in Consolidated Statements of Income	(4.3)	(7.7)	(1.5)
Unrecognized Pension Gain (Loss) Arising During the Year	11.5	(4.9)	(0.7)
Amortization of Accumulated Unrecognized Pension Loss	(4.3)	(2.6)	(6.3)
Comprehensive Pension Expense (Income)	2.9	$ (15.2)	$ (8.5)
Amounts that will be amortized from AOCI in next Fiscal Year	$ 2.6