Derivative Financial Instruments and Hedging Activities (Additional Information) (Details 1) - USD ($) $ in Thousands		3 Months Ended				12 Months Ended
		Aug. 31, 2009	May 31, 2008	Feb. 29, 2008	Aug. 31, 2007	Aug. 31, 2016	Aug. 31, 2015	Aug. 31, 2011	Feb. 28, 2011
Derivative [Line Items]
Hedge accounting adjustment related to terminated interest rate swaps	[1]						$ 2,077
7.750% Senior Notes Due 2016
Derivative [Line Items]
Senior unsecured notes, interest rate		7.75%
Expiry date		Jul. 15, 2016
7.750% Senior Notes Due 2016 | Interest rate swap | Fair value hedging
Derivative [Line Items]
Aggregate notional amount outstanding									$ 200,000
Fair value of interest rate swap including accrued interest on interest rate swap								$ 12,200
Accrued interest on interest rate swaps								$ 600
Amortization of interest rate swaps						$ 2,100
8.250% Senior Notes Due 2018
Derivative [Line Items]
Senior unsecured notes, interest rate			8.25%	8.25%
Expiry date			Mar. 15, 2018	Mar. 15, 2018
8.250% Senior Notes Due 2018 | Interest rate swap | Cash flow hedging
Derivative [Line Items]
Aggregate notional amount outstanding					$ 400,000
Payment to settle interest rate swaps					$ 43,100
Anticipated debt issuance [Member] | Forward starting swap [Member] | Cash flow hedging
Derivative [Line Items]
Aggregate notional amount outstanding						$ 200,000
Derivative expiration date						Mar. 15, 2018
Term loan facility [Member] | Interest rate swap | Cash flow hedging
Derivative [Line Items]
Aggregate notional amount outstanding						$ 200,000
Derivative expiration date						Jun. 30, 2019

[1] This amount represents the fair value hedge accounting adjustment related to the 7.750% Senior Notes. For further discussion of the Company’s fair value hedges, see Note 14 - “ Derivative Financial Instruments and Hedging Activities” to the Consolidated Financial Statements.