Intangibles and Other Assets, Net - Additional Information (Detail) - USD ($) $ in Millions	12 Months Ended
	Aug. 31, 2017	Aug. 31, 2016	Aug. 31, 2015
Schedule of Intangible Assets Disclosure [Line Items]
Amortization expense	$ 4.8	$ 6.3	$ 3.7
Future amortization expense, 2018	5.8
Future amortization expense, 2019	5.4
Future amortization expense, 2020	5.7
Future amortization expense, 2021	5.4
Future amortization expense, 2022	$ 4.0