Revenue (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Revenue from Contract with Customer, Excluding Assessed Tax	$ 1,055.1	$ 865.1	$ 861.6
REVENUE	1,070.6	876.5	861.0
RTO Revenue	156.9	120.5	88.5
RTO Capacity Revenue	5.4	0.9	3.5
Contract with Customer, Asset, before Allowance for Credit Loss	158.2	103.9
Utility [Member]
REVENUE	1,061.8	867.6	852.0
RTO Revenue	156.8	120.4	88.4
RTO Capacity Revenue	5.4	0.9	3.5
Corporate and Other
REVENUE	14.5	14.7	14.1
RTO Revenue	0.1	0.1	0.1
RTO Capacity Revenue	0.0	0.0	0.0
Adjustments and Eliminations
REVENUE	(5.7)	(5.8)	(5.1)
RTO Revenue	0.0	0.0	0.0
RTO Capacity Revenue	0.0	0.0	0.0
Wholesale Revenue [Member]
Revenue from Contract with Customer, Excluding Assessed Tax	27.7	16.6	15.1
Wholesale Revenue [Member] | Utility [Member]
Revenue from Contract with Customer, Excluding Assessed Tax	28.7	17.5	15.8
Wholesale Revenue [Member] | Corporate and Other
Revenue from Contract with Customer, Excluding Assessed Tax	0.0	0.0	0.0
Wholesale Revenue [Member] | Adjustments and Eliminations
Revenue from Contract with Customer, Excluding Assessed Tax	(1.0)	(0.9)	(0.7)
Other Revenues [Member]
Revenue from Contract with Customer, Excluding Assessed Tax	9.8	9.7	9.6
Other non-606 revenue	15.5	11.4	(0.6)
Other Revenues [Member] | Utility [Member]
Revenue from Contract with Customer, Excluding Assessed Tax	0.0	0.0	0.0
Other non-606 revenue	15.6	11.4	(0.6)
Other Revenues [Member] | Corporate and Other
Revenue from Contract with Customer, Excluding Assessed Tax	9.8	9.7	9.6
Other non-606 revenue	4.6	4.9	4.4
Other Revenues [Member] | Adjustments and Eliminations
Revenue from Contract with Customer, Excluding Assessed Tax	0.0	0.0	0.0
Other non-606 revenue	(4.7)	(4.9)	(4.4)
Retail Revenue [Member]
Revenue from Contract with Customer, Excluding Assessed Tax	855.3	717.4	744.9
Retail Revenue [Member] | Residential Revenue [Member]
Revenue from Contract with Customer, Excluding Assessed Tax	541.6	451.4	478.9
Retail Revenue [Member] | Commercial Revenue [Member]
Revenue from Contract with Customer, Excluding Assessed Tax	193.4	161.2	162.1
Retail Revenue [Member] | Industrial Revenue [Member]
Revenue from Contract with Customer, Excluding Assessed Tax	75.5	67.0	66.6
Retail Revenue [Member] | Governmental Revenue [Member]
Revenue from Contract with Customer, Excluding Assessed Tax	32.5	26.5	24.3
Retail Revenue [Member] | Other Revenues [Member]
Revenue from Contract with Customer, Excluding Assessed Tax	12.3	11.3	13.0
Retail Revenue [Member] | Utility [Member]
Revenue from Contract with Customer, Excluding Assessed Tax	855.3	717.4	744.9
Retail Revenue [Member] | Utility [Member] | Residential Revenue [Member]
Revenue from Contract with Customer, Excluding Assessed Tax	541.6	451.4	478.9
Retail Revenue [Member] | Utility [Member] | Commercial Revenue [Member]
Revenue from Contract with Customer, Excluding Assessed Tax	193.4	161.2	162.1
Retail Revenue [Member] | Utility [Member] | Industrial Revenue [Member]
Revenue from Contract with Customer, Excluding Assessed Tax	75.5	67.0	66.6
Retail Revenue [Member] | Utility [Member] | Governmental Revenue [Member]
Revenue from Contract with Customer, Excluding Assessed Tax	32.5	26.5	24.3
Retail Revenue [Member] | Utility [Member] | Other Revenues [Member]
Revenue from Contract with Customer, Excluding Assessed Tax	12.3	11.3	13.0
Retail Revenue [Member] | Corporate and Other
Revenue from Contract with Customer, Excluding Assessed Tax	0.0	0.0	0.0
Retail Revenue [Member] | Corporate and Other | Residential Revenue [Member]
Revenue from Contract with Customer, Excluding Assessed Tax	0.0	0.0	0.0
Retail Revenue [Member] | Corporate and Other | Commercial Revenue [Member]
Revenue from Contract with Customer, Excluding Assessed Tax	0.0	0.0	0.0
Retail Revenue [Member] | Corporate and Other | Industrial Revenue [Member]
Revenue from Contract with Customer, Excluding Assessed Tax	0.0	0.0	0.0
Retail Revenue [Member] | Corporate and Other | Governmental Revenue [Member]
Revenue from Contract with Customer, Excluding Assessed Tax	0.0	0.0	0.0
Retail Revenue [Member] | Corporate and Other | Other Revenues [Member]
Revenue from Contract with Customer, Excluding Assessed Tax	0.0	0.0	0.0
Retail Revenue [Member] | Adjustments and Eliminations
Revenue from Contract with Customer, Excluding Assessed Tax	0.0	0.0	0.0
Retail Revenue [Member] | Adjustments and Eliminations | Residential Revenue [Member]
Revenue from Contract with Customer, Excluding Assessed Tax	0.0	0.0	0.0
Retail Revenue [Member] | Adjustments and Eliminations | Commercial Revenue [Member]
Revenue from Contract with Customer, Excluding Assessed Tax	0.0	0.0	0.0
Retail Revenue [Member] | Adjustments and Eliminations | Industrial Revenue [Member]
Revenue from Contract with Customer, Excluding Assessed Tax	0.0	0.0	0.0
Retail Revenue [Member] | Adjustments and Eliminations | Governmental Revenue [Member]
Revenue from Contract with Customer, Excluding Assessed Tax	0.0	0.0	0.0
Retail Revenue [Member] | Adjustments and Eliminations | Other Revenues [Member]
Revenue from Contract with Customer, Excluding Assessed Tax	$ 0.0	$ 0.0	$ 0.0