Principal Payments on Notes Payable (Detail) - USD ($) $ in Thousands		Aug. 31, 2017	Aug. 31, 2016
Debt Instrument [Line Items]
2018	[1]	$ 130,263
2019		26,040
2020		166,301
2021		0
2022		0
Thereafter	[2]	275,000
Notes payable, gross		$ 597,604	$ 303,969

[1] The repayment of the $119.1 million of Convertible senior notes due 2018 is assumed to occur in stock at the scheduled maturity in 2018 instead of assuming an earlier conversion by the holders.

[2] The repayment of the $275.0 million of Convertible senior notes due 2024 is assumed to occur at the scheduled maturity in 2024 instead of assuming an earlier conversion by the holders.