Fair Value Measures - Assets and Liabilities Measured at Fair Value on Recurring Basis (Detail) - USD ($) $ in Thousands	Feb. 28, 2018		Nov. 30, 2017	Aug. 31, 2017
Assets:
Nonqualified savings plan investments			$ 24,710	$ 20,974
Fair Value, Measurements, Recurring
Assets:
Derivative financial instruments	$ 4,478			3,814
Nonqualified savings plan investments	24,710			20,974
Cash equivalents	105,791			105,337
Assets, Fair Value Disclosure, Total	134,979			130,125
Liabilities:
Derivative financial instruments	716			2,886
Fair Value, Inputs, Level 1 | Fair Value, Measurements, Recurring
Assets:
Nonqualified savings plan investments	24,710			20,974
Cash equivalents	105,791			105,337
Assets, Fair Value Disclosure, Total	130,501			126,311
Fair Value, Inputs, Level 2 | Fair Value, Measurements, Recurring
Assets:
Derivative financial instruments	4,478	[1]		3,814
Assets, Fair Value Disclosure, Total	4,478	[1]		3,814
Liabilities:
Derivative financial instruments	$ 716	[1]		$ 2,886

[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.