Defined Benefit and Postretirement Benefits Contributions by Plan Type (Details) $ in Millions	6 Months Ended
	Jun. 30, 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	1.9
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	2.5
Defined Benefit Plan, Plan Assets, Contributions by Employer	1.1
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