Earnings Per Common Share - Computation of EPS (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items]
Income (Loss) from Continuing Operations, Net of Tax, Attributable to Parent									$ (69.8)	$ 40.0	$ 102.7
Income (Loss) from Discontinued Operations, Net of Tax, Attributable to Parent									0.0	0.0	0.3
Numerator:
Net (loss) income	$ (30.0)	$ (17.7)	$ (13.8)	$ (8.3)	$ (11.9)	$ (11.0)	$ 2.3	$ 60.6	(69.8)	40.0	103.0
Preferred stock dividends									10.4	10.4	10.4
Net Income (Loss) Available to Common Stockholders, Basic and Diluted									$ (80.2)	$ 29.6	$ 92.6
Denominator:
Weighted Average Number of Shares Outstanding, Basic									46.3	42.2	42.0
Stock-based compensation arrangements									0.0	0.2	0.1
Weighted Average Number of Shares Outstanding, Diluted									46.3	42.4	42.1
Basic and diluted earnings per common share									$ (1.73)	$ 0.70	$ 2.20
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
Continuing Operations [Member]
Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items]
Income (Loss) from Continuing Operations, Net of Tax, Attributable to Parent									$ (69.8)	$ 40.0	$ 102.7
Numerator:
Preferred stock dividends									10.4	10.4	10.4
Net Income (Loss) Available to Common Stockholders, Basic and Diluted									$ (80.2)	$ 29.6	$ 92.3
Denominator:
Weighted Average Number of Shares Outstanding, Basic									46.3	42.2	42.0
Stock-based compensation arrangements									0.0	0.2	0.1
Weighted Average Number of Shares Outstanding, Diluted									46.3	42.4	42.1
Income (Loss) from Continuing Operations, Per Basic Share and Diluted Share									$ (1.73)	$ 0.70	$ 2.19
Discontinued Operations [Member]
Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items]
Income (Loss) from Discontinued Operations, Net of Tax, Attributable to Parent									$ 0.0	$ 0.0	$ 0.3
Numerator:
Preferred stock dividends									0.0	0.0	0.0
Net Income (Loss) Available to Common Stockholders, Basic and Diluted									$ 0.0	$ 0.0	$ 0.3
Denominator:
Weighted Average Number of Shares Outstanding, Basic									0.0	0.0	42.0
Stock-based compensation arrangements									0.0	0.0	0.1
Weighted Average Number of Shares Outstanding, Diluted									0.0	0.0	42.1
Income (Loss) from Discontinued Operations and Disposal of Discontinued Operations, Net of Tax, Per Basic Share and Diluted Share									$ 0.00	$ 0.00	$ 0.01