Benefit Plans (Amounts Recognized in Other Comprehensive Income (Loss)) (Details) - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014
Pension Benefits [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Net actuarial loss (gain)	$ 79.9	$ 120.1
Transition obligation	0.1	0.2
Prior service credit	(5.7)	(6.3)
Total	74.3	114.0
Other Retirement Benefits [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Net actuarial loss (gain)	(13.2)	(13.8)
Transition obligation	0.0	0.0
Prior service credit	0.0	0.0
Total	$ (13.2)	$ (13.8)