Impact of Derivative for Interest Rate Risk and Designated as Hedging Instrument on Accumulated Other Comprehensive Income (Loss) and Earnings (Detail) (Interest rate swap, Interest expense, USD $)	3 Months Ended
	Nov. 30, 2012	Nov. 30, 2011
Interest rate swap | Interest expense
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain (Loss) Recognized in OCI on Derivative (Effective Portion)	$ 0	$ 0
Amount of Gain (Loss) Reclassified from AOCI into Income (Effective Portion)	(988,000)	(988,000)
Amount of Gain (Loss) Recognized in Income on Derivative (Ineffective Portion and Amount Excluded from Effectiveness Testing)	$ 0	$ 0