Business Segments (Segment Financial Information) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023
Segment Reporting Information [Line Items]
Revenues	$ 226.4	$ 240.1
Depreciation and amortization	22.6	19.8
Interest expense	20.3	18.1
Total assets	2,987.7		$ 2,906.2
Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest	4.2	2.3
Utility [Member]
Segment Reporting Information [Line Items]
Revenues	224.3	237.8
Operating Segments [Member] | Utility [Member]
Segment Reporting Information [Line Items]
Revenues	224.3	237.8
Depreciation and amortization	22.1	19.4
Interest expense	11.2	8.3
Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest	11.7	10.9
Corporate, Non-Segment [Member]
Segment Reporting Information [Line Items]
Revenues	3.5	3.3
Depreciation and amortization	0.5	0.4
Interest expense	9.1	9.8
Total assets	31.8		35.2
Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest	(7.5)	(8.6)
Intersegment Eliminations
Segment Reporting Information [Line Items]
Revenues	(1.4)	(1.0)
Depreciation and amortization	0.0	0.0
Interest expense	0.0	0.0
Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest	0.0	0.0
Subsidiaries [Member]
Segment Reporting Information [Line Items]
Revenues	224.3	237.8
Depreciation and amortization	22.1	19.4
Interest expense	11.2	8.3
Total assets	2,955.9		$ 2,871.0
Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest	$ 11.7	$ 10.9