Derivative Financial Instruments and Hedging Activities - Schedule of Derivatives Instruments Statements of Financial Performance and Financial Position, Location (Details) - Designated as Hedging Instrument - Long-term debt - USD ($) $ in Thousands	May 31, 2018	Aug. 31, 2017
Derivative [Line Items]
Carrying Amount of Hedged Liabilities	$ 486,153	$ 504,271
Cumulative Amount of Fair Value Hedging Adjustments Included in the Carrying Amount of Hedged Liabilities	$ 8,847	$ (9,271)