Benefit Plans (Amounts Recognized in Balance Sheet) (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Current liabilities	$ (2.2)	$ (2.2)
Noncurrent liabilities	(53.4)	(75.6)
Pension Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Current liabilities	(1.5)	(1.5)
Noncurrent liabilities	(47.0)	(68.3)
Total liabilities	(48.5)	(69.8)
Other Postretirement Benefits Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Current liabilities	(0.7)	(0.7)
Noncurrent liabilities	(6.4)	(7.3)
Total liabilities	$ (7.1)	$ (8.0)