Acquisition - Summary of Pro Forma Information Related to Results of Operations (Detail) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended								12 Months Ended			6 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	Nov. 30, 2013 Rocketdyne Business [Member]	Nov. 30, 2013 Rocketdyne Business [Member]	Nov. 30, 2012 Rocketdyne Business [Member]	Nov. 30, 2011 Rocketdyne Business [Member]
Net sales:
As reported	$ 485.3	$ 367.5	$ 286.6	$ 243.7	$ 298.2	$ 244.9	$ 249.9	$ 201.9	$ 1,383.1	$ 994.9	$ 918.1	$ 319.4	$ 1,383.1	$ 994.9	$ 918.1
Pro forma													1,762.7	1,694.0	1,572.7
Net income (loss):
As reported	(3.7)	197.4	(11.8)	(14.0)	2.8	(9.5)	1.7	2.4	167.9	(2.6)	2.9	18.3	167.9	(2.6)	2.9
Pro forma													$ 30.7	$ 38.2	$ (142.1)
Basic EPS:
As reported	$ (0.06)	$ 3.25	$ (0.20)	$ (0.24)					$ 2.76	$ (0.04)	$ 0.05		$ 2.76	$ (0.04)	$ 0.05
Pro forma													$ 0.50	$ 0.64	$ (2.42)
Diluted EPS:
As reported	$ (0.06)	$ 2.39	$ (0.20)	$ (0.24)					$ 2.11	$ (0.04)	$ 0.05		$ 2.11	$ (0.04)	$ 0.05
Pro forma													$ 0.47	$ 0.56	$ (2.42)