Derivative Financial Instruments and Hedging Activities - Additional Information (Detail) (USD $)	3 Months Ended	6 Months Ended							3 Months Ended
	Aug. 31, 2007	Feb. 28, 2013	Aug. 31, 2012	Feb. 28, 2011	Feb. 28, 2013 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	Aug. 31, 2007 8.250% Senior Notes Due 2018	Feb. 28, 2013 8.250% Senior Notes Due 2018	Aug. 31, 2012 8.250% Senior Notes Due 2018
Derivative [Line Items]
Aggregate notional amount outstanding of foreign currency denominated revenues and expenses designated as cash flow hedges		$ 447,200,000	$ 199,700,000
Aggregate notional amount outstanding of forward contracts to hedge transactional exposure		1,000,000,000	837,300,000
Amount estimated 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					7.75%	7.75%		7.75%	8.25%	8.25%	8.25%
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		1,200,000
Hedge accounting adjustment related to terminated interest rate swaps		8,010,000	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