Intangibles and Other Assets, Net - Additional Information (Detail) - USD ($) $ in Millions	12 Months Ended
	Aug. 31, 2018	Aug. 31, 2017	Aug. 31, 2016
Schedule of Intangible Assets Disclosure [Line Items]
Amortization expense	$ 5.3	$ 4.8	$ 6.3
Future amortization expense, 2019	5.2
Future amortization expense, 2020	5.2
Future amortization expense, 2021	4.8
Future amortization expense, 2022	3.4
Future amortization expense, 2023	$ 3.2