Employee Benefits (Narrative) (Details) $ in Millions	3 Months Ended
	Mar. 31, 2018 USD ($)
Pension Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Contributions by Employer	$ 2.0
Estimated Future Employer Contributions in Current Fiscal Year	2.0
SERP [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Contributions by Employer	0.2
Estimated Future Employer Contributions in Current Fiscal Year	0.5
Medical Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Contributions by Employer	0.1
Estimated Future Employer Contributions in Current Fiscal Year	$ 0.1