Debt (Narrative) (Details) (USD $)	3 Months Ended		12 Months Ended			12 Months Ended		3 Months Ended		12 Months Ended		12 Months Ended				12 Months Ended
	Aug. 31, 2013	Feb. 28, 2013	Aug. 31, 2013	Aug. 31, 2014	Aug. 31, 2014 Co-Issuers And Guarantor [Member]	Aug. 31, 2014 2013 Fixed Rate Notes [Member]	Aug. 31, 2013 2013 Fixed Rate Notes [Member]	Aug. 31, 2013 2011 Fixed Rate Notes [Member]	Feb. 28, 2013 2011 Fixed Rate Notes [Member]	Aug. 31, 2014 2011 Fixed Rate Notes [Member]	May 20, 2011 2011 Fixed Rate Notes [Member]	Aug. 31, 2014 2011 Variable Rate Notes [Member]	Aug. 31, 2013 2011 Variable Rate Notes [Member]	May 31, 2013 2011 Variable Rate Notes [Member]	May 20, 2011 2011 Variable Rate Notes [Member]	Aug. 31, 2014 2011 Notes [Member]	Aug. 31, 2014 Interest Rate Upward Adjustment Due To Nonpayment [Member]
Debt Instrument [Line Items]
Future maturities of long-term debt, 2015				$ 9,800,000
Future maturities of long-term debt, 2016				9,800,000
Future maturities of long-term debt, 2017				9,800,000
Future maturities of long-term debt, 2018				253,000,000
Future maturities of long-term debt, 2019				0
Debt instrument, face amount							155,000,000				500,000,000				100,000,000
Debt issuance date																May 20, 2011
Debt prepayment								155,000,000	20,000,000
Senior secured notes interest rate, percentage							3.75%			5.40%							5.00%
Debt instrument, maturity year						Jul. 20, 2020				May 21, 2018		May 21, 2018
Long-term Debt	447,294,000		447,294,000	437,318,000								0	0
Long term debt fixed rate notes including accrued interest carrying value	447,600,000		447,600,000	437,800,000		155,200,000	155,200,000	292,400,000		282,600,000
Weighted-average interest cost, percentage						4.10%				5.70%
Expected life of debt instrument						7 years				7 years
Interest rate percentage												3.50%		3.75%
Debt instrument, legal final maturity year						Jul. 20, 2043										May 20, 2041
Annual commitment fee payable, percentage												0.50%
Proceeds from borrowings			155,000,000
Payment of loan costs							4,100,000
Total assets	660,794,000		660,794,000	650,972,000	319,900,000
Restricted cash				19,900,000	19,900,000
Gain (loss) from early extinguishment of debt	$ (3,900,000)	$ (500,000)	$ (4,443,000)