Assets and Liabilities Measured at Fair Value on Recurring Basis (Detail) - USD ($) $ in Thousands		Aug. 31, 2017	Aug. 31, 2016
Assets:
Nonqualified savings plan investments		$ 20,974	$ 15,864
Fair Value, Measurements, Recurring
Assets:
Derivative financial instruments		3,814	1,595
Nonqualified savings plan investments		20,974	15,864
Cash equivalents		105,337	5,077
Assets, Fair Value Disclosure, Total		130,125	22,536
Liabilities:
Derivative financial instruments		2,886	7,466
Fair Value, Inputs, Level 1 | Fair Value, Measurements, Recurring
Assets:
Nonqualified savings plan investments		20,974	15,864
Cash equivalents		105,337	5,077
Assets, Fair Value Disclosure, Total		126,311	20,941
Fair Value, Inputs, Level 2 | Fair Value, Measurements, Recurring
Assets:
Derivative financial instruments	[1]	3,814	1,595
Assets, Fair Value Disclosure, Total	[1]	3,814	1,595
Liabilities:
Derivative financial instruments	[1]	$ 2,886	$ 7,466

[1] Level 2 assets include derivative financial instruments which are valued based on significant observable inputs. See Note 14 Derivative Instruments for further discussion.