Derivative Financial Instruments and Hedging Activities - Additional Information (Detail) (USD $)	3 Months Ended					3 Months Ended
	Nov. 30, 2012	Aug. 31, 2007	Aug. 31, 2012	Nov. 30, 2011	Feb. 28, 2011	Aug. 31, 2007 8.250% Senior Notes Due 2018	Nov. 30, 2012 8.250% Senior Notes Due 2018	Aug. 31, 2012 8.250% Senior Notes Due 2018	Nov. 30, 2012 7.750% Senior Notes Due 2016	Aug. 31, 2012 7.750% Senior Notes Due 2016	Aug. 31, 2011 7.750% Senior Notes Due 2016	Feb. 28, 2011 7.750% Senior Notes Due 2016
Derivative [Line Items]
Aggregate notional amount outstanding of foreign currency denominated revenues and expenses designated as cash flow hedges	$ 430,300,000			$ 255,700,000
Aggregate notional amount outstanding of forward contracts to hedge transactional exposure	991,700,000			779,500,000
Estimated gain to reclassify into earnings during the next 12 months related to foreign currency risk management hedging arrangements	900,000
Notional amount of interest rate swaps designated as fair value hedges					200,000,000
Senior unsecured notes, interest rate						8.25%	8.25%	8.25%	7.75%	7.75%		7.75%
Fair value adjustment related to interest rate swap including accrued interest on interest rate swaps											12,200,000
Accrued interest on interest rate swaps											600,000
Amortization of interest rate swaps	600,000
Hedge accounting adjustment related to terminated interest rate swaps	8,604,000		9,197,000
Notional amount of interest rate swaps designated as cash flow hedges		400,000,000
Payment to settle interest rate swaps		43,100,000
Expiry date						Mar. 15, 2018
Amount estimated to reclassify into earnings during the next 12 months related to interest rate risk management hedging arrangements	$ 4,000,000