Retirement Benefits (Details 9) $ in Millions	Dec. 31, 2023 USD ($)
Defined Benefit Plan Disclosure [Line Items]
Amortization of prior service cost (credit)	$ (0.5)
Amortization of net actuarial loss	5.3
Amortization of accumulated other comprehensive loss	4.8
Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Amortization of prior service cost (credit)	0.4
Amortization of net actuarial loss	0.0
Amortization of accumulated other comprehensive loss	0.4
Other Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Amortization of prior service cost (credit)	(0.9)
Amortization of net actuarial loss	5.3
Amortization of accumulated other comprehensive loss	$ 4.4