Summary of Significant Accounting Policies - Schedule of Impact of Contracts in Progress on Statement of Operations (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, Basic, by Common Class, Including Two Class Method [Line Items]
Favorable effect of the changes in contract estimates on (loss) income 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
Favorable effect of the changes in contract estimates on 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
Favorable effect of the changes in contract estimates on basic income (loss) per share	$ (0.06)	$ 3.25	$ (0.20)	$ (0.24)					$ 2.76	$ (0.04)	$ 0.05
Favorable effect of the changes in contract estimates on diluted income (loss) per share	$ (0.06)	$ 2.39	$ (0.20)	$ (0.24)					$ 2.11	$ (0.04)	$ 0.05
Contracts Accounted for Under Percentage-of-Completion [Member]
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Favorable effect of the changes in contract estimates on (loss) income from continuing operations									18.4	8.9	3.9
Favorable effect of the changes in contract estimates on net income (loss)									$ 10.8	$ 5.3	$ 2.4
Favorable effect of the changes in contract estimates on basic income (loss) per share									$ 0.18	$ 0.09	$ 0.04
Favorable effect of the changes in contract estimates on diluted income (loss) per share									$ 0.13	$ 0.09	$ 0.04