Restatement - Summary of the Impact to Pretax Income (Loss) from Continuing Operations by Reporting Period (Details) - USD ($) $ 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
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Income (loss) before income taxes	$ 15.5	$ (60.2)	$ 37.2	$ (9.3)	$ 26.6	$ (11.2)	$ (48.2)	$ (0.2)	$ 27.9	$ (48.4)	$ (32.3)	$ (59.6)	$ (16.8)	$ (33.0)	$ (35.7)
Contract Accounting [Member]
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Income (loss) before income taxes											0.0			1.9	(2.0)
Other Individually Immaterial Items [Member]
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Income (loss) before income taxes											(1.2)			(1.5)	0.3
Rocketdyne Business [Member] | Purchase Accounting [Member]
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Income (loss) before income taxes											(0.5)			3.1	(7.8)
Rocketdyne Business [Member] | Contract Accounting [Member]
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Income (loss) before income taxes											$ 1.3			$ 2.9	$ 0.0