Condensed Consolidated Statements of Comprehensive Income - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2025	Mar. 31, 2024
Net income	$ 2.7	$ 2.6
Derivative activity:
Reclassification of earnings, net of income tax	(0.2)	(0.2)
Pension and postretirement activity:
Reclassification to earnings, net of income tax	0.2	0.0
Other comprehensive loss	0.0	(0.2)
NET COMPREHENSIVE INCOME	2.7	2.4
Subsidiaries [Member]
Net income	10.7	9.4
Pension and postretirement activity:
Reclassification to earnings, net of income tax	0.5	0.4
Other comprehensive loss	0.5	0.4
NET COMPREHENSIVE INCOME	11.2	$ 9.8
Retained Earnings [Member] | Subsidiaries [Member]
Net income	10.7
Accumulated Net Gain (Loss) from Cash Flow Hedges Attributable to Parent [Member]
Pension and postretirement activity:
Other comprehensive loss	(0.2)
Change in unfunded pension obligation [Member]
Pension and postretirement activity:
Other comprehensive loss	$ 0.2