Net Periodic Benefit Costs (Detail) - Domestic Plan [Member] - USD ($) $ in Thousands	12 Months Ended
	Aug. 31, 2018	Aug. 31, 2017	Aug. 31, 2016
Defined Benefit Plan Disclosure [Line Items]
Interest cost	$ 1,633	$ 1,690	$ 1,970
Expected return on assets	(2,668)	(2,867)	(2,997)
Amortization of actuarial loss	$ 1,127	$ 1,141	$ 837