U.S. Pension Plan Investment Allocations by Asset Category (Detail) - USD ($) $ in Thousands	Aug. 31, 2019	Aug. 31, 2018
Schedule of Pension Plan Assets by Fair Value [Line Items]
Defined Benefit Plan, Plan Assets, Amount	$ 40,412	$ 40,244
Percentage of fair value of pension plan assets	100.00%	100.00%
Cash and cash equivalents | Fair Value, Inputs, Level 1
Schedule of Pension Plan Assets by Fair Value [Line Items]
Defined Benefit Plan, Plan Assets, Amount	$ 304	$ 559
Percentage of fair value of pension plan assets	0.80%	1.40%
Fixed Income Securities | Fair Value, Inputs, Level 2
Schedule of Pension Plan Assets by Fair Value [Line Items]
Defined Benefit Plan, Plan Assets, Amount	$ 28,333	$ 19,921
Percentage of fair value of pension plan assets	70.10%	49.50%
Fixed Income Securities | Corporate Bond Securities | Fair Value, Inputs, Level 2
Schedule of Pension Plan Assets by Fair Value [Line Items]
Defined Benefit Plan, Plan Assets, Amount	$ 5,127	$ 19,107
Percentage of fair value of pension plan assets	12.70%	47.50%
Fixed Income Securities | Mutual Funds | Fair Value, Inputs, Level 2
Schedule of Pension Plan Assets by Fair Value [Line Items]
Defined Benefit Plan, Plan Assets, Amount	$ 23,206	$ 814
Percentage of fair value of pension plan assets	57.40%	2.00%
Equity Securities | Mutual Funds | Fair Value, Inputs, Level 1
Schedule of Pension Plan Assets by Fair Value [Line Items]
Defined Benefit Plan, Plan Assets, Amount	$ 11,775	$ 19,764
Percentage of fair value of pension plan assets	29.10%	49.10%