Benefit Plans (Amounts Recognized in Other Comprehensive Income (Loss)) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Pension Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Net actuarial loss (gain)	$ 73.0	$ 74.5
Prior service credit	0.9	(0.8)
Total	73.9	73.7
Defined Benefit Plan, Excess of Net Periodic Benefit Cost Over Other Comprehensive Income	7.1	0.3	$ 18.9
Other Postretirement Benefits Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Net actuarial loss (gain)	(9.4)	(10.4)
Prior service credit	(1.7)	(2.4)
Total	(11.1)	(12.8)
Defined Benefit Plan, Excess of Net Periodic Benefit Cost Over Other Comprehensive Income	$ (1.2)	$ (0.8)	$ (2.1)