Income (Loss) Per Share of Common Stock - Summary of Reconciliation of Numerator and Denominator Used to Calculate Basic and Diluted Loss Per Share of Common Stock (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	1 Months Ended		3 Months Ended								12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Nov. 30, 2015	Aug. 31, 2015	May 31, 2015	Feb. 28, 2015	Dec. 31, 2016	Nov. 30, 2015	Nov. 30, 2014
Numerator:
Income (loss) from continuing operations	$ 7.0		$ 18.0	$ (11.0)	$ 5.9	$ 5.2	$ 7.6	$ (38.5)	$ 17.3	$ (3.5)	$ 18.1	$ (17.1)	$ (49.3)
(Loss) income from discontinued operations, net of income taxes	0.0		0.1	(0.1)	0.0	(0.1)	0.1	0.6	0.0	0.2	(0.1)	0.9	(0.7)
Net income (loss)	7.0	$ (6.2)	$ 18.1	$ (11.1)	$ 5.9	$ 5.1	$ 7.7	$ (37.9)	$ 17.3	$ (3.3)	18.0	(16.2)	(50.0)
Income allocated to participating securities	(0.2)										(0.4)	0.0	0.0
Net income (loss) for basic earnings per share	6.8										17.6	(16.2)	(50.0)
Interest on 4 1/16% Debentures	0.3										0.0	0.0	0.0
Net income (loss) for diluted earnings per share	$ 7.1										$ 17.6	$ (16.2)	$ (50.0)
Denominator:
Basic weighted average shares (in shares)	62.9										65.6	61.1	57.9
Effect of:
Convertible subordinated notes (in shares)	9.4										0.0	0.0	0.0
Employee stock options (in shares)	0.2										0.1	0.0	0.0
Diluted weighted average shares (in shares)	72.5										65.7	61.1	57.9
Basic:
(Loss) income per share from continuing operations (in USD per share)	$ 0.11	$ (0.11)	$ 0.26	$ (0.17)	$ 0.09	$ 0.08	$ 0.12	$ (0.62)	$ 0.28	$ (0.06)	$ 0.27	$ (0.28)	$ (0.85)
Income (loss) per share from discontinued operations, net of income taxes (in USD per share)	0.00		0.00	0.00	0.00	0.00	0.00	0.01	0.00	0.00	0.00	0.01	(0.01)
Net (loss) income per share (in USD per share)	0.11	(0.11)	0.26	(0.17)	0.09	0.08	0.12	(0.61)	0.28	(0.06)	0.27	(0.27)	(0.86)
Diluted:
(Loss) income per share from continuing operations (in USD per share)	0.10	(0.11)	0.25	(0.17)	0.09	0.08	0.12	(0.62)	0.25	(0.06)	0.27	(0.28)	(0.85)
Income (loss) per share from discontinued operations, net of income taxes (in USD per share)	0.00		0.00	0.00	0.00	0.00	0.00	0.01	0.00	0.00	0.00	0.01	(0.01)
Net (loss) income per share (in USD per share)	$ 0.10	$ (0.11)	$ 0.25	$ (0.17)	$ 0.09	$ 0.08	$ 0.12	$ (0.61)	$ 0.25	$ (0.06)	$ 0.27	$ (0.27)	$ (0.86)