Net Income Per Share (Schedule of Income Per Share) (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Income Per Share Calculation [Line Items]
Net income	$ 84.4	$ 52.2	$ 175.0
Preferred stock dividends, undeclared and cumulative	0.0	0.0	2.1
Net income (loss) allocable to common stockholders	$ 84.4	$ 50.7	$ 135.3
Average number of shares outstanding, basic	15,212	14,601	13,493
Potentially dilutive shares related to stock options	289	387	386
Average number of shares outstanding, diluted	15,501	14,988	13,879
Net income (loss) per common share - basic	$ 5.55	$ 3.47	$ 10.03
Net income (loss) per common share - diluted	$ 5.44	$ 3.38	$ 9.75
Exchange of preferred stock for common stock and common stock warrant			$ 0.0
Preferred Stock Dividends and Other Adjustments	$ 0.0		37.6
Distributed earnings allocable to warrant modification	0.0	$ 1.5	0.0
Accumulated Deficit [Member]
Income Per Share Calculation [Line Items]
Net income	84.4	52.2	175.0
Exchange of preferred stock for common stock and common stock warrant			(7.6)
Distributed earnings allocable to warrant modification	$ 0.0	$ 1.5	$ 0.0