Income (Loss) Per Share of Common Stock - Reconciliation of Numerator and Denominator Used to Calculate Basic and Diluted Income (Loss) Per Share (Detail) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Nov. 30, 2013	Aug. 31, 2013	May 31, 2013	Feb. 28, 2013	Nov. 30, 2012	Aug. 31, 2012	May 31, 2012	Feb. 29, 2012	Nov. 30, 2013	Nov. 30, 2012	Nov. 30, 2011
Earnings Per Share [Abstract]
Income (loss) from continuing operations	$ (4.1)	$ 197.6	$ (11.7)	$ (14.1)	$ (0.7)	$ (8.7)	$ 1.3	$ 2.4	$ 167.7	$ (5.7)	$ 2.9
Income from discontinued operations, net of income taxes	0.4	(0.2)	(0.1)	0.1	3.5	(0.8)	0.4		0.2	3.1
Net income (loss)	(3.7)	197.4	(11.8)	(14.0)	2.8	(9.5)	1.7	2.4	167.9	(2.6)	2.9
Income allocated to participating securities									(3.2)
Net income (loss) for basic earnings per share									164.7	(2.6)	2.9
Interest on convertible subordinated debentures									8.1
Net income (loss) for diluted earnings per share									$ 172.8	$ (2.6)	$ 2.9
Denominator:
Basic weighted average shares									59.6	59.0	58.7
Effect of:
Convertible subordinated notes									22.1
Employee stock options									0.2
Diluted weighted average shares									81.9	59.0	58.7
Basic EPS:
Income (loss) per share from continuing operations	$ (0.07)	$ 3.25	$ (0.20)	$ (0.24)					$ 2.76	$ (0.09)	$ 0.05
Income from discontinued operations, net of income taxes										$ 0.05
Net income (loss) per share	$ (0.06)	$ 3.25	$ (0.20)	$ (0.24)					$ 2.76	$ (0.04)	$ 0.05
Diluted EPS:
Income (loss) per share from continuing operations	$ (0.07)	$ 2.39	$ (0.20)	$ (0.24)					$ 2.11	$ (0.09)	$ 0.05
Income from discontinued operations, net of income taxes										$ 0.05
Net income (loss) per share	$ (0.06)	$ 2.39	$ (0.20)	$ (0.24)					$ 2.11	$ (0.04)	$ 0.05