Benefit Plans, Amounts Recognized in Consolidated Balance Sheet (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Amounts recognized in Balance Sheet [Abstract]
Current liability	$ (55.4)	$ (61.3)
Non-current liability	(155.0)	(147.3)
Pension Benefits [Member]
Amounts recognized in Balance Sheet [Abstract]
Current liability	(0.8)	(0.8)
Non-current liability	(148.5)	(137.8)
Recognized liability	(149.3)	(138.6)
Post-retirement Benefits [Member]
Amounts recognized in Balance Sheet [Abstract]
Current liability	(0.5)	(0.6)
Non-current liability	(6.4)	(8.7)
Recognized liability	$ (6.9)	$ (9.3)