Derivative Financial Instruments and Hedging Activities - Schedule of Derivative Instruments in Statement of Financial Position, Fair Value (Details) - USD ($) $ in Thousands	Feb. 28, 2018	Aug. 31, 2017
Derivative [Line Items]
Derivative Assets	$ 452,708	$ 418,952
Derivative Liabilities	380,615	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	$ 8,616	$ 707