Condensed Consolidated Statements of Operations - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Revenues	$ 148.1	$ 155.1	$ 323.3	$ 326.3
Operating costs and expenses
Net fuel cost	0.1	0.3	0.5	0.9
Utilities Operating Expense, Purchased Power	53.9	49.2	125.4	112.0
Operating expenses:
Operation and maintenance	38.0	43.8	72.8	90.8
Depreciation and amortization	18.9	18.5	38.0	36.2
Taxes other than income taxes	20.7	21.0	41.1	41.9
Costs and Expenses	131.6	132.8	277.8	281.8
Operating income	16.5	22.3	45.5	44.5
Other expense, net:
Interest expense	(15.6)	(19.4)	(31.2)	(38.3)
Other income / (expense)	0.6	0.8	1.1	(0.1)
Total other expense, net	(15.0)	(18.6)	(30.1)	(38.4)
Income from continuing operations before income tax	1.5	3.7	15.4	6.1
Income tax expense from continuing operations	0.9	2.8	0.6	2.7
Net income from continuing operations	0.6	0.9	14.8	3.4
Loss from discontinued operations before income tax	(0.2)	(1.2)	(1.0)	(2.0)
Income tax expense / (benefit) from discontinued operations	0.0	0.7	(0.2)	0.5
Net income / (loss) from discontinued operations	(0.2)	2.6	(0.8)	2.0
Net income	0.4	3.5	14.0	5.4
Subsidiaries [Member]
Revenues	145.9	153.1	318.7	322.1
Operating costs and expenses
Net fuel cost	0.1	0.3	0.5	0.9
Utilities Operating Expense, Purchased Power	53.6	49.0	124.8	111.4
Operating expenses:
Operation and maintenance	37.7	42.9	72.3	89.9
Depreciation and amortization	18.5	18.2	37.2	35.5
Taxes other than income taxes	20.7	21.0	41.0	41.8
Costs and Expenses	130.6	131.4	275.8	279.5
Operating income	15.3	21.7	42.9	42.6
Other expense, net:
Interest expense	(6.0)	(6.4)	(12.0)	(12.6)
Other income / (expense)	(0.2)	0.2	(0.3)	(1.6)
Total other expense, net	(6.2)	(6.2)	(12.3)	(14.2)
Income from continuing operations before income tax	9.1	15.5	30.6	28.4
Income tax expense from continuing operations	0.5	(2.3)	3.7	(1.1)
Net income	$ 8.6	$ 17.8	$ 26.9	$ 29.5