(Loss) Income Per Share of Common Stock, (As Restated for fiscal 2014 and 2013) - 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	3 Months Ended								6 Months Ended		9 Months Ended		12 Months Ended
	Nov. 30, 2015	Aug. 31, 2015	May. 31, 2015	Feb. 28, 2015	Nov. 30, 2014	Aug. 31, 2014	May. 31, 2014	Feb. 28, 2014	May. 31, 2015	May. 31, 2014	Aug. 31, 2015	Aug. 31, 2014	Nov. 30, 2015	Nov. 30, 2014	Nov. 30, 2013
Numerator:
(Loss) income from continuing operations	$ 7.6	$ (38.5)	$ 17.3	$ (3.5)	$ 12.0	$ (10.7)	$ (48.4)	$ (2.2)	$ 13.8	$ (50.6)	$ (24.7)	$ (61.3)	$ (17.1)	$ (49.3)	$ 162.7
Income (loss) from discontinued operations, net of income taxes	0.1	0.6	0.0	0.2	(0.1)	0.2	(0.8)	0.0	0.2	(0.8)	0.8	(0.6)	0.9	(0.7)	0.2
Net (loss) income	$ 7.7	$ (37.9)	$ 17.3	$ (3.3)	$ 11.9	$ (10.5)	$ (49.2)	$ (2.2)	$ 14.0	$ (51.4)	$ (23.9)	$ (61.9)	(16.2)	(50.0)	162.9
Income allocated to participating securities													0.0	0.0	(3.1)
Net (loss) income for basic earnings per share													(16.2)	(50.0)	159.8
Interest on convertible subordinated debentures													0.0	0.0	8.1
Net (loss) income for diluted earnings per share													$ (16.2)	$ (50.0)	$ 167.9
Denominator:
Basic weighted average shares (in shares)			61.2	58.9	56.9				59.9				61.1	57.9	59.6
Effect of:
Convertible subordinated notes (in shares)													0.0	0.0	22.1
Employee stock options (in shares)													0.0	0.0	0.2
Diluted weighted average shares (in shares)			72.3	58.9	72.0				72.2				61.1	57.9	81.9
Basic:
(Loss) income per share from continuing operations (in USD per share)	$ 0.12	$ (0.62)	$ 0.28	$ (0.06)	$ 0.20	$ (0.19)	$ (0.84)	$ (0.04)	$ 0.23				$ (0.28)	$ (0.85)	$ 2.68
Income (loss) per share from discontinued operations, net of income taxes (in USD per share)	0.00	0.01	0.00	0.00	0.00	0.00	(0.01)	0.00	0.00				0.01	(0.01)	0.00
Net (loss) income per share (in USD per share)	0.12	(0.61)	0.28	(0.06)	0.20	(0.19)	(0.85)	(0.04)	0.23				(0.27)	(0.86)	2.68
Diluted:
(Loss) income per share from continuing operations (in USD per share)	0.12	(0.62)	0.25	(0.06)	0.18	(0.19)	(0.84)	(0.04)	0.22				(0.28)	(0.85)	2.05
Income (loss) per share from discontinued operations, net of income taxes (in USD per share)	0.00	0.01	0.00	0.00	0.00	0.00	(0.01)	0.00	0.00				0.01	(0.01)	0.00
Net (loss) income per share (in USD per share)	$ 0.12	$ (0.61)	$ 0.25	$ (0.06)	$ 0.18	$ (0.19)	$ (0.85)	$ (0.04)	$ 0.22				$ (0.27)	$ (0.86)	$ 2.05