Employee Benefits (Narrative) (Details) $ in Millions	3 Months Ended
	Mar. 31, 2018 USD ($)
Retirement Plans
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Employer Contribution	$ 2.9
Defined Benefit Plan, Expected Future Employer Contributions, Current Fiscal Year	9.4
Other Postretirement Benefit Plans
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Employer Contribution	0.1
Defined Benefit Plan, Expected Future Employer Contributions, Current Fiscal Year	$ 0.5