Derivatives Gains (Losses) included in Other Comprehensive Income in Derivatives Accounted for as Hedging Instruments, Net of Tax (Details) - USD ($) $ in Thousands	12 Months Ended
	Aug. 31, 2015	Aug. 31, 2014	Aug. 31, 2013
Derivative Instruments, Gain (Loss) [Line Items]
Interest rate derivatives	$ (4,078)	$ (10,580)	$ 24,135
Interest Expense [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Interest rate derivatives	$ (792)	$ 12,727	$ (907)