Earnings Per Common Share - Computation of Basic and Diluted Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Numerator:
Net loss	$ (3.0)	$ (34.0)
Preferred stock dividends	2.6	2.6
Net loss applicable to common shareowners - basic and diluted	$ (5.6)	$ (36.6)
Denominator:
Weighted average common shares outstanding - basic	50.8	50.5
Stock-based compensation arrangements	0.0	0.0
Weighted average common shares outstanding - diluted	50.8	50.5
Basic and diluted net loss per common share	$ (0.11)	$ (0.72)