Derivative Financial Instruments and Hedging Activities - Fair Value of Derivative Instruments Located on Consolidated Balance Sheets (Details) - Forward foreign exchange contracts - USD ($) $ in Thousands	Feb. 28, 2019	Aug. 31, 2018
Designated as Hedging Instruments | Prepaid expenses and other current assets
Derivatives, Fair Value [Line Items]
Forward foreign exchange contracts, Asset Derivatives	$ 6,560	$ 225
Designated as Hedging Instruments | Accrued expenses
Derivatives, Fair Value [Line Items]
Forward foreign exchange contracts, Liability Derivatives	1,104	13,364
Derivatives Not Designated as Hedging Instruments Under ASC 815 | Prepaid expenses and other current assets
Derivatives, Fair Value [Line Items]
Forward foreign exchange contracts, Asset Derivatives	24,422	10,125
Derivatives Not Designated as Hedging Instruments Under ASC 815 | Accrued expenses
Derivatives, Fair Value [Line Items]
Forward foreign exchange contracts, Liability Derivatives	$ 3,602	$ 46,171