Income Per Share - Computation of Earnings Per Common Share and Fully Diluted Earnings Per Common Share (Detail) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended
	Feb. 28, 2013	Feb. 29, 2012
Earnings Per Share [Abstract]
Weighted Average Number of Shares Outstanding, Including Participating Shares, Basic	46.1	45.9
Undistributed Earnings Allocated to Participating Securities	$ 0	$ 0.4
Weighted-average participating shares outstanding	0.1	1.2
Undistributed Earnings From Continuing Operations Allocated To Participating Securities Diluted	0	0.4
Basic Earnings Per Share:
Income From Continuing Operations	0.2	10.7
Income from continuing operations allocated to common stockholders	0	0.4
Income from continuing operations allocated to common stockholders	0.2	10.3
Income (loss) from discontinued operations	(0.4)	2.8
Undistributed Earnings From Discontinued Operations Allocated To Participating Securities Basic	0	0
Income (loss) from discontinued operations allocated to common stockholders	(0.4)	2.8
Net Income (loss)	(0.2)	13.5
Net income allocated to common stockholders	(0.2)	13.1
Weighted average shares outstanding - Basic	46.0	44.7
Income from continuing operations income per common share - basic	$ 0.00	$ 0.23
Income (loss) from discontinued operations per common share - basic	$ 0.00	$ 0.06
Net income per common share - basic	$ 0.00	$ 0.29
Diluted Earnings Per Share:
Income From Continuing Operations	0.2	10.7
Income from continuing operations allocated to common stockholders	0.2	10.3
Income (loss) from discontinued operations	(0.4)	2.8
Income (loss) from discontinued operations allocated to participating securities	0	0
Income (loss) from discontinued operations allocated to common stockholders	(0.4)	2.8
Net Income (loss)	(0.2)	13.5
Net income allocated to participating securities	0	0.4
Net income allocated to common stockholders	$ (0.2)	$ 13.1
Weighted average shares outstanding - Basic	46.0	44.7
Dilutive effect of stock options	0.6	0.1
Weighted-average common shares outstanding - assuming dilution	46.7	46.0
Income from continuing operations per common share - assuming dilution	$ 0.00	$ 0.23
Income (loss) from discontinued operations per common share - assuming dilution	$ 0.00	$ 0.06
Net income per common share - assuming dilution	$ 0.00	$ 0.29