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 $) In Thousands, unless otherwise specified	9 Months Ended
	May 31, 2012	May 31, 2011
Interest rate swap | Interest expense
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain (Loss) Recognized in OCI on Derivative (Effective Portion)
Amount of Gain (Loss) Reclassified from AOCI into Income (Effective Portion)	(2,963)	(2,963)
Amount of Gain (Loss) Recognized in Income on Derivative (Ineffective Portion and Amount Excluded from Effectiveness Testing)