Contingencies and Litigation - Additional Information (Details) - USD ($) $ in Millions	Nov. 30, 2017	Aug. 31, 2017
Commitments and Contingencies Disclosure [Abstract]
Outstanding letters of credit	$ 14.3	$ 14.5
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Discounted present value of future minimum lease payments	$ 12.8
Weighted Average Discount Rate on Future Minimum Lease Payments	2.62%