Basis of Presentation and Nature of Operations - Narrative - Out of Period Adjustments (Details) - USD ($) $ in Millions	3 Months Ended					6 Months Ended		9 Months Ended
	May. 31, 2015	Feb. 28, 2015	Aug. 31, 2014	May. 31, 2014	Feb. 28, 2014	May. 31, 2015	May. 31, 2014	Aug. 31, 2014
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Increase in (loss) income from continuing operations before income taxes	$ 39.7		$ (11.1)	$ (50.7)	$ (0.5)	$ 29.0	$ (51.2)
Net income (loss)	18.4		$ (9.9)	$ (50.9)	$ (2.3)	14.5	$ (53.2)	$ (63.1)
Restatement Adjustment [Member]
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Net impact of out of period adjustments, income from continuing operations before income taxes, understating (overstating)	(1.8)	$ 2.1				0.0
Net impact of out of period adjustments, net income, understating (overstating)	(1.1)	1.3				$ 0.2
Restatement Adjustment [Member] | Rocketdyne Business [Member]
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Increase in (loss) income from continuing operations before income taxes	1.8	(1.1)
Net income (loss)	$ 1.1	$ (0.7)