Credit Arrangements (Long-term debt, including the deferred gain from the termination of the interest rate swaps) (Details) (USD $)			12 Months Ended		12 Months Ended
	Aug. 31, 2013	Aug. 31, 2012	Aug. 31, 2012 $200 million notes at 5.625% due November 2013	Aug. 31, 2013 $200 million notes at 5.625% due November 2013	Aug. 31, 2013 $400 million notes at 6.50% due July 2017	Aug. 31, 2012 $400 million notes at 6.50% due July 2017	Aug. 31, 2013 $500 million notes at 7.35% due August 2018	Aug. 31, 2012 $500 million notes at 7.35% due August 2018	Aug. 31, 2013 $330 million notes at 4.875% due May 2023	May 31, 2013 $330 million notes at 4.875% due May 2023	Aug. 31, 2012 $330 million notes at 4.875% due May 2023	Aug. 31, 2013 Other, including equipment notes [Member]	Aug. 31, 2012 Other, including equipment notes [Member]
Debt Instrument [Line Items]
Debt instrument, face amount			$ 200,000,000	$ 200,000,000	$ 400,000,000	$ 400,000,000	$ 500,000,000	$ 500,000,000	$ 330,000,000	$ 330,000,000
Debt Instrument, Interest Rate, Stated Percentage			5.625%	5.625%	6.50%	6.50%	7.35%	7.35%	4.875%	4.875%
Debt instrument, maturity date			November 2013		July 2017	July 2017	August 2018	August 2018	May 15, 2023
Weighted average interest rate				0.00%	5.70%		6.40%		4.90%
Total long-term debt including current maturities	1,284,042,000	1,161,325,000	204,873,000	0	411,518,000	414,491,000	522,930,000	527,554,000	330,000,000		0	19,594,000	14,407,000
Current maturities of long-term debt	5,228,000	4,252,000
Long-term debt	$ 1,278,814,000	$ 1,157,073,000