Condensed Consolidated Statements of Operations - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Revenues	$ 209.2	$ 202.0	$ 435.6	$ 442.1
OPERATING COSTS AND EXPENSES:
Net purchased power cost	69.5	87.5	159.2	209.7
Operation and maintenance	61.1	60.1	122.0	114.1
Depreciation and amortization	21.1	20.5	43.7	40.3
Taxes other than income taxes	27.1	26.7	56.3	52.2
Loss on asset disposal	0.0	0.0	1.3	0.0
Costs and Expenses	178.8	194.8	382.5	416.3
OPERATING INCOME	30.4	7.2	53.1	25.8
OTHER INCOME / (EXPENSE), NET:
Interest expense, net	(20.8)	(19.3)	(41.1)	(37.4)
Other income, net	1.9	1.5	3.7	3.3
Total other expense, net	(18.9)	(17.8)	(37.4)	(34.1)
Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest	11.5	(10.6)	15.7	(8.3)
Income tax expense / (benefit)	1.3	(5.4)	2.9	(4.3)
NET INCOME / (LOSS)	10.2	(5.2)	12.8	(4.0)
Subsidiaries [Member]
Revenues	206.9	199.7	431.2	437.5
OPERATING COSTS AND EXPENSES:
Net purchased power cost	69.2	87.2	158.7	209.2
Operation and maintenance	60.8	59.2	121.5	112.4
Depreciation and amortization	20.7	20.2	42.8	39.6
Taxes other than income taxes	26.9	26.6	56.1	52.1
Loss on asset disposal	0.0	0.0	1.1	0.0
Costs and Expenses	177.6	193.2	380.2	413.3
OPERATING INCOME	29.3	6.5	51.0	24.2
OTHER INCOME / (EXPENSE), NET:
Interest expense, net	(11.7)	(9.7)	(22.9)	(18.0)
Other income, net	1.3	1.3	2.5	2.8
Total other expense, net	(10.4)	(8.4)	(20.4)	(15.2)
Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest	18.9	(1.9)	30.6	9.0
Income tax expense / (benefit)	3.8	(1.5)	6.1	(0.2)
NET INCOME / (LOSS)	$ 15.1	$ (0.4)	$ 24.5	$ 9.2