Condensed Consolidated Statements of Comprehensive Income - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Net income	$ (19.7)	$ 8.5	$ (4.1)	$ 22.5
Derivative activity:
Reclassification of earnings, net of income tax	(0.1)	(0.2)	(0.5)	(0.6)
Total change in fair value of derivatives	(0.1)	(0.2)	(0.5)	(0.6)
Pension and postretirement activity:
Reclassification to earnings, net of income tax	0.2	0.5	0.7	1.5
Total change in unfunded pension obligation	0.2	0.5	0.7	1.5
Other comprehensive income	0.1	0.3	0.2	0.9
Comprehensive income / (loss)	(19.6)	8.8	(3.9)	23.4
Subsidiaries [Member]
Net income	(10.1)	13.4	14.1	40.3
Pension and postretirement activity:
Reclassification to earnings, net of income tax	0.6	1.0	2.0	2.9
Total change in unfunded pension obligation	0.6	1.0	2.0	2.9
Other comprehensive income	0.6	1.0	2.0	2.9
Comprehensive income / (loss)	(9.5)	14.4	16.1	43.2
Change in unfunded pension obligation [Member] | Subsidiaries [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member]
Net income	$ (0.6)	$ (1.0)	$ (2.0)	$ (2.9)