Segment Information (Reconciliation of Operating Profit from Segment to Consolidated) (Details) - USD ($) $ in Millions	3 Months Ended		12 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020
Segment Reporting [Abstract]
Operating income from continuing operations	$ 21.0	$ 5.0
Less: interest expense	14.5	18.1
Less: net pension income	(4.1)	(2.7)
Gain on debt extinguishment	0.0	(0.6)	$ (0.6)
Loss before income taxes and equity in loss (earnings) of unconsolidated entity	$ 10.6	$ (9.8)