Net Income Per Share (Schedule of Income Per Share) (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Millions	3 Months Ended						9 Months Ended
	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Sep. 30, 2020	Sep. 30, 2019
Income Per Share Calculation [Line Items]
Net income (loss)	$ (7.0)	$ 33.7	$ 11.3	$ 22.8	$ (15.6)	$ (20.9)	$ 38.0	$ (13.7)
Preferred stock dividends, undeclared and cumulative	1.9			1.9			5.9	5.9
Net income (loss) allocable to common stockholders	$ (8.9)			$ 20.9			$ 32.1	$ (19.6)
Average number of shares outstanding, basic	10,723			9,582			10,008	9,560
Potentially dilutive shares related to stock options	0			44			274	0
Average number of shares outstanding, diluted	10,723			9,626			10,282	9,560
Net income (loss) per common share - basic	$ (0.83)			$ 2.18			$ 3.21	$ (2.05)
Net income (loss) per common share - diluted	$ (0.83)			$ 2.17			$ 3.12	$ (2.05)
Antidilutive securities excluded from computation of earnings per share	317			0			0	67
Options with exercise price greater than market price	0			460			0	460