Pension and Other Postretirement Benefit Plans Contributions by Plan Type (Details) $ in Millions	3 Months Ended
	Mar. 31, 2019 USD ($)
Pension Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Expected Future Employer Contributions, Current Fiscal Year	$ 3.1
Defined Benefit Plan, Plan Assets, Contributions by Employer	1.4
Other Postretirement Benefits Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Expected Future Employer Contributions, Current Fiscal Year	0.7
Defined Benefit Plan, Plan Assets, Contributions by Employer	0.8
Supplemental Employee Retirement Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Expected Future Employer Contributions, Current Fiscal Year	2.2
Defined Benefit Plan, Plan Assets, Contributions by Employer	$ 2.1