Assets and Liabilities Measured at Fair Value on Recurring Basis (Detail) - USD ($) $ in Thousands	Feb. 28, 2017		Aug. 31, 2016
Assets:
Nonqualified savings plan investments	$ 20,056		$ 15,864
Fair Value, Measurements, Recurring
Assets:
Derivative financial instruments	232		1,595
Nonqualified savings plan investments	20,056		15,864
Cash equivalents	5,078		5,077
Assets, Fair Value Disclosure, Total	25,366		22,536
Liabilities:
Derivative financial instruments	8,896		7,466
Fair Value, Inputs, Level 1 | Fair Value, Measurements, Recurring
Assets:
Nonqualified savings plan investments	20,056		15,864
Cash equivalents	5,078		5,077
Assets, Fair Value Disclosure, Total	25,134		20,941
Fair Value, Inputs, Level 2 | Fair Value, Measurements, Recurring
Assets:
Derivative financial instruments	232	[1]	1,595
Assets, Fair Value Disclosure, Total	232	[1]	1,595
Liabilities:
Derivative financial instruments	$ 8,896	[1]	$ 7,466

[1] Level 2 assets and liabilities include derivative financial instruments that are valued based on observable inputs. See Note 11 Derivative Instruments for further discussion.