Benefit Plans (Pension and Postretirement Benefit Plans' Obligations and Assets) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Defined Benefit Plan, Benefit Obligation, Actuarial Gain (Loss)	$ 2.7	$ (12.4)
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Noncurrent liabilities	(16.5)	(30.7)
Postretirement [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Defined Benefit Plan, Funded (Unfunded) Status of Plan	8.6	7.9
Pension [Member]
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Benefit obligation at January 1	282.4	298.6
Service cost	2.2	2.5	$ 3.0
Interest cost	14.5	14.6	15.8
Defined Benefit Plan, Benefit Obligation, Actuarial Gain (Loss)	2.7	(12.4)
Benefit obligation at December 31	266.0	282.4	298.6
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets at January 1	260.1	268.4
Actual return / (loss) on plan assets	26.5	5.0
Contributions to plan assets	7.7	7.6
Fair value of plan assets at December 31	258.5	260.1	$ 268.4
Defined Benefit Plan, Funded (Unfunded) Status of Plan	(7.5)	(22.3)
Current liabilities	(0.2)	(0.2)
Noncurrent liabilities	(7.3)	(22.1)
Net asset / (liability) at December 31	(7.5)	(22.3)
Prior service cost	5.7	6.7
Net actuarial loss	62.7	74.0
Accumulated other comprehensive income, regulatory assets and regulatory liabilities, pre-tax	68.4	80.7
Defined Benefit Plan, Plan Assets, Benefits Paid	35.8	20.9
Defined Benefit Plan, Benefit Obligation, Benefits Paid	35.8	20.9
Regulatory Asset [Member] | Pension [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Accumulated other comprehensive income, regulatory assets and regulatory liabilities, pre-tax	47.5	56.0
Accumulated Other Comprehensive Income/(Loss) [Member] | Pension [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Accumulated other comprehensive income, regulatory assets and regulatory liabilities, pre-tax	$ 20.9	$ 24.7