Contingencies and Litigation - Additional Information (Detail) - USD ($) $ in Millions	Aug. 31, 2016	Aug. 31, 2015
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Outstanding letters of credit	$ 17.8	$ 18.1
Discounted present value of future minimum lease payments	16.0
Electrical
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Discounted present value of future minimum lease payments	$ 12.3