Derivative Financial Instruments and Hedging Activities - Schedule of Derivative Instruments in Statement of Financial Position, Fair Value (Details) - USD ($) $ in Thousands	May 31, 2018	Aug. 31, 2017
Derivative [Line Items]
Derivative Assets	$ 505,861	$ 418,952
Derivative Liabilities	353,451	329,693
Designated as Hedging Instrument | Other Assets | Interest rate swap derivatives
Derivative [Line Items]
Derivative Assets	0	9,978
Designated as Hedging Instrument | Other Liabilities | Interest rate swap derivatives
Derivative [Line Items]
Derivative Liabilities	$ 8,847	$ 707