Postretirement Benefits Other Than Pensions - Components Of Comprehensive OPEB (Income) Expense (Details) - Other Postretirement Benefit Plan, Defined Benefit - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Defined Benefit Plan Disclosure [Line Items]
Service Cost Earned During the Year	$ 0.1	$ 0.1	$ 0.2
Interest Cost on Accumulated Postretirement Benefit Obligation	0.3	0.4	0.2
Amortization of Prior Service Credit	(1.3)	(1.3)	(1.3)
Amortization of Accumulated Unrecognized OPEB Gain	(1.5)	(1.8)	(1.8)
Pension (Income) Expense Recognized in Consolidated Statements of Income (Loss)	(2.4)	(2.6)	(2.7)
Unrecognized OPEB Gain Arising During the Year	(1.0)	(0.1)	(2.5)
Prior Service Cost Arising During the Year	1.3	1.3	1.3
Amortization of Accumulated Unrecognized OPEB Gain	1.5	1.8	1.8
Comprehensive OPEB (Income) Expense	$ (0.6)	$ 0.4	$ (2.1)