Condensed Consolidated Statements of Operations - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Revenues	$ 199.3	$ 175.2
Operating costs and expenses
Net fuel cost	0.0	0.4
Utilities Operating Expense, Purchased Power	90.8	71.5
Operating expenses:
Operation and maintenance	40.8	34.8
Depreciation and amortization	19.5	19.1
Taxes other than income taxes	22.0	20.4
Gain (Loss) on Sale of Assets and Asset Impairment Charges, excluding Discontinued Operations	(0.6)	0.0
Costs and Expenses	172.5	146.2
Operating income	26.8	29.0
Other expense, net:
Interest expense	(15.5)	(15.6)
Other income	0.4	0.5
Total other expense, net	(15.1)	(15.1)
Income from continuing operations before income tax	11.7	13.9
Income tax benefit from continuing operations	(3.7)	(0.3)
Net income from continuing operations	15.4	14.2
Loss from discontinued operations before income tax	0.0	(0.8)
Income tax benefit from discontinued operations	0.0	(0.2)
Net loss from discontinued operations	0.0	(0.6)
Net income	15.4	13.6
Subsidiaries [Member]
Revenues	197.0	172.8
Operating costs and expenses
Net fuel cost	0.0	0.4
Utilities Operating Expense, Purchased Power	90.5	71.2
Operating expenses:
Operation and maintenance	40.2	34.6
Depreciation and amortization	19.2	18.7
Taxes other than income taxes	21.9	20.3
Gain (Loss) on Sale of Assets and Asset Impairment Charges, excluding Discontinued Operations	(0.6)	0.0
Costs and Expenses	171.2	145.2
Operating income	25.8	27.6
Other expense, net:
Interest expense	(5.9)	(6.0)
Other income	(0.3)	(0.1)
Total other expense, net	(6.2)	(6.1)
Income from continuing operations before income tax	19.6	21.5
Income tax benefit from continuing operations	2.7	3.2
Net income	$ 16.9	$ 18.3