Derivative Instruments - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Nov. 30, 2012
Derivative [Line Items]
Interest rates, that would be reclassified to interest expense in the next 12 months	$ 1.6
Foreign Currency Forward Exchange Contracts
Derivative [Line Items]
Aggregate notional amount of foreign currency derivatives	78.4
Unrealized pre-tax loss	2.6
Interest Rate Swap
Derivative [Line Items]
Unrealized pre-tax loss	2.5
Notional amount of interest rate swap	$ 42.6
Maturity date	2014-03