Basis of Presentation and Nature of Operations - Summary of Impact from Changes in Estimates and Assumptions on Statements of Operations on Contracts (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended				6 Months Ended		9 Months Ended
	May. 31, 2015	Aug. 31, 2014	May. 31, 2014	Feb. 28, 2014	May. 31, 2015	May. 31, 2014	Aug. 31, 2014
Change in Accounting Estimate [Line Items]
Favorable (unfavorable) effect of the changes in contract estimates on income (loss) from continuing operations before income taxes	$ 18.4	$ (10.1)	$ (50.1)	$ (2.3)	$ 14.3	$ (52.4)
Favorable (unfavorable) effect of the changes in contract estimates on net income (loss)	$ 18.4	$ (9.9)	$ (50.9)	$ (2.3)	$ 14.5	$ (53.2)	$ (63.1)
Favorable (unfavorable) effect of the changes in contract estimates on basic and diluted net loss per share (in USD per share)	$ 0.29	$ (0.18)	$ (0.88)	$ (0.04)	$ 0.23	$ (0.91)
Favorable (unfavorable) effect of the changes in contract estimates on diluted net income (loss) per share (in USD per share)	$ 0.26		$ (0.88)		$ 0.22	$ (0.91)
Contracts Accounted for under Percentage-of-Completion [Member]
Change in Accounting Estimate [Line Items]
Favorable (unfavorable) effect of the changes in contract estimates on income (loss) from continuing operations before income taxes	$ 7.0		$ (5.2)		$ 7.2	$ (2.9)
Favorable (unfavorable) effect of the changes in contract estimates on net income (loss)	$ 4.2		$ (3.1)		$ 4.3	$ (1.6)
Favorable (unfavorable) effect of the changes in contract estimates on basic and diluted net loss per share (in USD per share)	$ 0.07		$ (0.05)		$ 0.07	$ (0.03)
Favorable (unfavorable) effect of the changes in contract estimates on diluted net income (loss) per share (in USD per share)	$ 0.06		$ (0.05)		$ 0.06	$ (0.03)