Employee Benefits Schedule of Fair Values of Pension and Postretirement Benefit Assets by Asset Class (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Plan Assets, Amount	$ 113.9	$ 93.3
Defined Benefit Plan, Plan Assets, Actual Allocation, Percentage	100.00%	100.00%
Cash and short-term investments [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Plan Assets, Amount	$ 0.6	$ 0.7
Defined Benefit Plan, Plan Assets, Actual Allocation, Percentage	1.00%	1.00%
Domestic equity securities [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Plan Assets, Amount	$ 30.6	$ 20.7
Defined Benefit Plan, Plan Assets, Actual Allocation, Percentage	27.00%	22.00%
International equity securities [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Plan Assets, Amount	$ 10.5	$ 10.0
Defined Benefit Plan, Plan Assets, Actual Allocation, Percentage	9.00%	11.00%
Fixed income securities [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Plan Assets, Amount	$ 72.2	$ 61.9
Defined Benefit Plan, Plan Assets, Actual Allocation, Percentage	63.00%	66.00%