Retirement Benefits (Details 9) $ in Millions	Dec. 31, 2018 USD ($)
Defined Benefit Plan Disclosure [Line Items]
Amortization of prior service cost (credit)	$ (2.6)
Amortization of net actuarial loss	87.1
Amortization of accumulated other comprehensive loss	84.5
Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Amortization of prior service cost (credit)	0.3
Amortization of net actuarial loss	73.7
Amortization of accumulated other comprehensive loss	74.0
Other Postretirement Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Amortization of prior service cost (credit)	(2.9)
Amortization of net actuarial loss	13.4
Amortization of accumulated other comprehensive loss	$ 10.5