Derivative Financial Instruments and Hedging Activities Gains (Losses) Included in Other Comprehensive Income on Derivatives Accounted for as Hedging Instruments, Net of Tax (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Feb. 28, 2015	Feb. 28, 2014	Feb. 28, 2015	Feb. 28, 2014
Derivative Instruments, Gain (Loss) [Line Items]
Interest rate derivatives	$ (3,702)	$ (5,299)	$ (4,296)	$ (10,580)