Revenue (Details) - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2026	Mar. 31, 2025	Dec. 31, 2025
Revenue from Contract with Customer, Excluding Assessed Tax	$ 338.4	$ 250.8
RTO Revenue	47.3	37.6
RTO Capacity Revenue	2.1	0.3
Revenues	341.1	254.3
Contract with Customer, Asset, before Allowance for Credit Loss	174.6		$ 158.2
Utility [Member]
RTO Revenue	47.2	37.6
RTO Capacity Revenue	2.1	0.3
Revenues	338.7	252.1
Corporate and Other
RTO Revenue	0.1	0.0
RTO Capacity Revenue	0.0	0.0
Revenues	3.8	3.7
Adjustments and Eliminations
RTO Revenue	0.0	0.0
RTO Capacity Revenue	0.0	0.0
Revenues	(1.4)	(1.5)
Other Revenues [Member]
Revenue from Contract with Customer, Excluding Assessed Tax	2.6	2.5
Other non-606 revenue	2.7	3.5
Other Revenues [Member] \| Utility [Member]
Revenue from Contract with Customer, Excluding Assessed Tax	0.0	0.0
Other non-606 revenue	2.7	3.5
Other Revenues [Member] \| Corporate and Other
Revenue from Contract with Customer, Excluding Assessed Tax	2.6	2.5
Other non-606 revenue	1.1	1.2
Other Revenues [Member] \| Adjustments and Eliminations
Revenue from Contract with Customer, Excluding Assessed Tax	0.0	0.0
Other non-606 revenue	(1.1)	(1.2)
Wholesale Revenue [Member]
Revenue from Contract with Customer, Excluding Assessed Tax	15.8	8.9
Wholesale Revenue [Member] \| Utility [Member]
Revenue from Contract with Customer, Excluding Assessed Tax	16.1	9.2
Wholesale Revenue [Member] \| Corporate and Other
Revenue from Contract with Customer, Excluding Assessed Tax	0.0	0.0
Wholesale Revenue [Member] \| Adjustments and Eliminations
Revenue from Contract with Customer, Excluding Assessed Tax	(0.3)	(0.3)
Retail Revenue [Member]
Revenue from Contract with Customer, Excluding Assessed Tax	270.6	201.5
Retail Revenue [Member] \| Residential Revenue
Revenue from Contract with Customer, Excluding Assessed Tax	179.8	136.7
Retail Revenue [Member] \| Commercial Revenue
Revenue from Contract with Customer, Excluding Assessed Tax	56.8	39.8
Retail Revenue [Member] \| Industrial Revenue
Revenue from Contract with Customer, Excluding Assessed Tax	20.9	15.7
Retail Revenue [Member] \| Governmental Revenue
Revenue from Contract with Customer, Excluding Assessed Tax	9.6	7.0
Retail Revenue [Member] \| Other Revenues [Member]
Revenue from Contract with Customer, Excluding Assessed Tax	3.5	2.3
Retail Revenue [Member] \| Utility [Member]
Revenue from Contract with Customer, Excluding Assessed Tax	270.6	201.5
Retail Revenue [Member] \| Utility [Member] \| Residential Revenue
Revenue from Contract with Customer, Excluding Assessed Tax	179.8	136.7
Retail Revenue [Member] \| Utility [Member] \| Commercial Revenue
Revenue from Contract with Customer, Excluding Assessed Tax	56.8	39.8
Retail Revenue [Member] \| Utility [Member] \| Industrial Revenue
Revenue from Contract with Customer, Excluding Assessed Tax	20.9	15.7
Retail Revenue [Member] \| Utility [Member] \| Governmental Revenue
Revenue from Contract with Customer, Excluding Assessed Tax	9.6	7.0
Retail Revenue [Member] \| Utility [Member] \| Other Revenues [Member]
Revenue from Contract with Customer, Excluding Assessed Tax	3.5	2.3
Retail Revenue [Member] \| Corporate and Other
Revenue from Contract with Customer, Excluding Assessed Tax	0.0	0.0
Retail Revenue [Member] \| Corporate and Other \| Residential Revenue
Revenue from Contract with Customer, Excluding Assessed Tax	0.0	0.0
Retail Revenue [Member] \| Corporate and Other \| Commercial Revenue
Revenue from Contract with Customer, Excluding Assessed Tax	0.0	0.0
Retail Revenue [Member] \| Corporate and Other \| Industrial Revenue
Revenue from Contract with Customer, Excluding Assessed Tax	0.0	0.0
Retail Revenue [Member] \| Corporate and Other \| Governmental Revenue
Revenue from Contract with Customer, Excluding Assessed Tax	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
Retail Revenue [Member] \| Adjustments and Eliminations
Revenue from Contract with Customer, Excluding Assessed Tax	0.0	0.0
Retail Revenue [Member] \| Adjustments and Eliminations \| Residential Revenue
Revenue from Contract with Customer, Excluding Assessed Tax	0.0	0.0
Retail Revenue [Member] \| Adjustments and Eliminations \| Commercial Revenue
Revenue from Contract with Customer, Excluding Assessed Tax	0.0	0.0
Retail Revenue [Member] \| Adjustments and Eliminations \| Industrial Revenue
Revenue from Contract with Customer, Excluding Assessed Tax	0.0	0.0
Retail Revenue [Member] \| Adjustments and Eliminations \| Governmental Revenue
Revenue from Contract with Customer, Excluding Assessed Tax	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