Derivative Financial Instruments and Hedging Activities - Schedule of Derivative Instruments, Effect on Earnings (Details) - Designated as Hedging Instrument - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Feb. 28, 2018	Feb. 28, 2017	Feb. 28, 2018	Feb. 28, 2017
Derivative [Line Items]
Gain (loss) on fair value hedging relationship	$ 0	$ 0	$ 0	$ 0
Interest Expense | Interest rate swap derivatives
Derivative [Line Items]
Gain (loss) on fair value hedging relationship	(9,571)	(4,237)	(17,888)	(17,513)
Interest Expense | Hedged Item
Derivative [Line Items]
Gain (loss) on fair value hedging relationship	$ 9,571	$ 4,237	$ 17,888	$ 17,513