Pension Benefits, Other Postretirement Benefits and Employee Savings and Investment Plans (PBO and ABO for Pension Plan and for Postretirement Benefit Plan) (Details) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Defined Benefit Plan Disclosure [Line Items]
PBO of plan assets for pension plan with plan assets in excess of its ABO	$ 21.5	$ 21.0
PBO of plan assets for pension plan with plan assets in excess of its PBO	21.5	21.0
ABO of plan assets for pension plan with plan assets in excess of its PBO	21.5	21.0
ABO of plan assets for pension plan with plan assets in excess of its ABO	21.5	21.0
Fair value of the plan assets for pension plan with plan assets in excess of its PBO	26.7	26.3
Fair value of the plan assets for pension plan with plan assets in excess of its ABO	26.7	26.3
Other Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
PBO of plan assets for pension plan with plan assets in excess of its ABO	(1.6)	(1.4)
PBO of plan assets for pension plan with plan assets in excess of its PBO	(1.6)	(1.4)
ABO of plan assets for pension plan with plan assets in excess of its PBO	(1.6)	(1.4)
ABO of plan assets for pension plan with plan assets in excess of its ABO	(1.6)	(1.4)
Fair value of the plan assets for pension plan with plan assets in excess of its PBO	0.0	0.0
Fair value of the plan assets for pension plan with plan assets in excess of its ABO	$ 0.0	$ 0.0