Retirement Benefits (Details 6) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Noncurrent assets	$ 9.2	$ 2.1
Current liabilities	(4.7)	(5.3)
Noncurrent liabilities	(730.0)	(697.0)
Total amount recognized	(725.5)	(700.2)
Other Postretirement Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Noncurrent assets	0.0	0.0
Current liabilities	(40.6)	(31.5)
Noncurrent liabilities	(318.4)	(317.8)
Total amount recognized	$ (359.0)	$ (349.3)