Earnings Per Common Share (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Numerator:
Net (loss) income	$ (17.7)	$ (11.0)	$ (39.8)	$ 51.9
Preferred stock dividends	2.6	2.6	7.8	7.8
Net (loss) income applicable to common shareowners - basic and diluted	$ (20.3)	$ (13.6)	$ (47.6)	$ 44.1
Denominator:
Weighted average common shares outstanding - basic	50.1	42.2	45.0	42.1
Stock-based compensation arrangements	0.0	0.0	0.0	0.2
Weighted average common shares outstanding - diluted	50.1	42.2	45.0	42.3
Basic net (loss) earnings per common share	$ (0.41)	$ (0.32)	$ (1.06)	$ 1.05
Diluted net (loss) earnings per common share	$ (0.41)	$ (0.32)	$ (1.06)	$ 1.04
Business Acquisition, Equity Interest Issued or Issuable, Number of Shares	7.7
Stock Issued During Period, Shares, Restricted Stock Award, Net of Forfeitures	0.1
Stock Compensation Plan [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount				0.2
Convertible Preferred Stock [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	0.9	0.9	0.9	0.9