Condensed Consolidated Statements of Operations - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Revenues	$ 190.9	$ 148.1	$ 390.2	$ 323.3
Operating costs and expenses
Net fuel cost	0.0	0.1	0.0	0.5
Utilities Operating Expense, Purchased Power	90.6	53.9	181.4	125.4
Operating expenses:
Operation and maintenance	43.1	38.0	83.9	72.8
Depreciation and amortization	20.1	18.9	39.6	38.0
Taxes other than income taxes	21.2	20.7	43.2	41.1
Gain (Loss) on Sale of Assets and Asset Impairment Charges, excluding Discontinued Operations	0.0	0.0	(0.6)	0.0
Costs and Expenses	175.0	131.6	347.5	277.8
Operating income	15.9	16.5	42.7	45.5
Other expense, net:
Interest expense	(16.5)	(15.6)	(32.0)	(31.2)
Other income	0.0	0.6	0.4	1.1
Total other expense, net	(16.5)	(15.0)	(31.6)	(30.1)
Income / (loss) from continuing operations before income tax	(0.6)	1.5	11.1	15.4
Income tax expense / (benefit) from continuing operations	(0.8)	0.9	(4.5)	0.6
Net income from continuing operations	0.2	0.6	15.6	14.8
Loss from discontinued operations before income tax	0.0	(0.2)	0.0	(1.0)
Income tax benefit from discontinued operations	0.0	0.0	0.0	(0.2)
Net loss from discontinued operations	0.0	(0.2)	0.0	(0.8)
Net income	0.2	0.4	15.6	14.0
Subsidiaries [Member]
Revenues	188.7	145.9	385.7	318.7
Operating costs and expenses
Net fuel cost	0.0	0.1	0.0	0.5
Utilities Operating Expense, Purchased Power	90.3	53.6	180.8	124.8
Operating expenses:
Operation and maintenance	42.9	37.7	83.1	72.3
Depreciation and amortization	19.7	18.5	38.9	37.2
Taxes other than income taxes	21.1	20.7	43.0	41.0
Gain (Loss) on Sale of Assets and Asset Impairment Charges, excluding Discontinued Operations	0.0	0.0	(0.6)	0.0
Costs and Expenses	174.0	130.6	345.2	275.8
Operating income	14.7	15.3	40.5	42.9
Other expense, net:
Interest expense	(6.8)	(6.0)	(12.7)	(12.0)
Other income	(0.6)	(0.2)	(0.9)	(0.3)
Total other expense, net	(7.4)	(6.2)	(13.6)	(12.3)
Income / (loss) from continuing operations before income tax	7.3	9.1	26.9	30.6
Income tax expense / (benefit) from continuing operations	0.0	0.5	2.7	3.7
Net income	$ 7.3	$ 8.6	$ 24.2	$ 26.9