Condensed Consolidated Statements of Operations - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Revenues	$ 202.0	$ 190.9	$ 442.1	$ 390.2
Operating costs and expenses:
Utilities Operating Expense, Purchased Power	87.5	90.6	209.7	181.4
Operating expenses:
Operation and maintenance	60.1	43.1	114.1	83.9
Depreciation and amortization	20.5	20.1	40.3	39.6
Taxes other than income taxes	26.7	21.2	52.2	43.2
Gain (Loss) on Sale of Assets and Asset Impairment Charges, excluding Discontinued Operations	0.0	0.0	0.0	(0.6)
Costs and Expenses	194.8	175.0	416.3	347.5
Operating income	7.2	15.9	25.8	42.7
Other income / (expense), net:
Interest expense	(19.3)	(16.5)	(37.4)	(32.0)
Other Nonoperating Income (Expense)	1.5	0.0	3.3	0.4
Total other expense, net	(17.8)	(16.5)	(34.1)	(31.6)
Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest	(10.6)	(0.6)	(8.3)	11.1
Income tax benefit	(5.4)	(0.8)	(4.3)	(4.5)
Net income / (loss)	(5.2)	0.2	(4.0)	15.6
Subsidiaries [Member]
Revenues	199.7	188.7	437.5	385.7
Operating costs and expenses:
Utilities Operating Expense, Purchased Power	87.2	90.3	209.2	180.8
Operating expenses:
Operation and maintenance	59.2	42.9	112.4	83.1
Depreciation and amortization	20.2	19.7	39.6	38.9
Taxes other than income taxes	26.6	21.1	52.1	43.0
Gain (Loss) on Sale of Assets and Asset Impairment Charges, excluding Discontinued Operations	0.0	0.0	0.0	(0.6)
Costs and Expenses	193.2	174.0	413.3	345.2
Operating income	6.5	14.7	24.2	40.5
Other income / (expense), net:
Interest expense	(9.7)	(6.8)	(18.0)	(12.7)
Other Nonoperating Income (Expense)	1.3	(0.6)	2.8	(0.9)
Total other expense, net	(8.4)	(7.4)	(15.2)	(13.6)
Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest	(1.9)	7.3	9.0	26.9
Income tax benefit	(1.5)	0.0	(0.2)	2.7
Net income / (loss)	$ (0.4)	$ 7.3	$ 9.2	$ 24.2