Credit Arrangements (Long-term Debt, Including the Net Effect of the Deferred Gain from the Termination of the Interest Rate Swaps) (Details) (USD $)	12 Months Ended
	Aug. 31, 2012		Aug. 31, 2011
Debt Instrument [Line Items]
Total long-term debt including current maturities	$ 1,161,325,000		$ 1,226,405,000
Current maturities of long-term debt	4,252,000		58,908,000
Long-term debt	1,157,073,000		1,167,497,000
5.625% notes due November 2013 [Member]
Debt Instrument [Line Items]
Debt instrument, face amount	200,000,000		200,000,000
Debt instrument, interest rate, stated percentage	5.625%		5.625%
Debt instrument, maturity date	November 2013		November 2013
Weighted average interest rate	3.50%	[1]
Total long-term debt including current maturities	204,873,000	[1]	207,752,000	[1]
6.50% notes due July 2017 [Member]
Debt Instrument [Line Items]
Debt instrument, face amount	400,000,000		400,000,000
Debt instrument, interest rate, stated percentage	6.50%		6.50%
Debt instrument, maturity date	July 2017		July 2017
Weighted average interest rate	5.70%	[1]
Total long-term debt including current maturities	414,491,000	[1]	414,198,000	[1]
7.35% notes due August 2018 [Member]
Debt Instrument [Line Items]
Debt instrument, face amount	500,000,000		500,000,000
Debt instrument, interest rate, stated percentage	7.35%		7.35%
Debt instrument, maturity date	August 2018		August 2018
Weighted average interest rate	6.40%	[1]
Total long-term debt including current maturities	527,554,000	[1]	526,699,000	[1]
Other, including equipment notes [Member]
Debt Instrument [Line Items]
Total long-term debt including current maturities	14,407,000		10,632,000
CMCZ term note [Member]
Debt Instrument [Line Items]
Total long-term debt including current maturities	0		48,648,000
CMCS financing agreement [Member]
Debt Instrument [Line Items]
Total long-term debt including current maturities	$ 0		$ 18,476,000

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