CREDIT ARRANGEMENTS (Narrative) (Details) (USD $)	12 Months Ended						12 Months Ended			12 Months Ended		12 Months Ended		12 Months Ended
	Aug. 31, 2014	Aug. 31, 2013	Aug. 31, 2012	Aug. 31, 2014 CMCP	Aug. 31, 2014 Revolving credit agreement	Aug. 31, 2014 Stand-by letters of credit	Aug. 31, 2014 $330 million notes at 4.875% due May 2023	Aug. 31, 2013 $330 million notes at 4.875% due May 2023	Aug. 31, 2014 Change of control triggering event	Aug. 31, 2013 $200 million notes at 5.625% due November 2013	May 31, 2013 $200 million notes at 5.625% due November 2013	Aug. 31, 2014 $500 million notes at 7.35% due August 2018	Aug. 31, 2013 $500 million notes at 7.35% due August 2018	Aug. 31, 2014 $400 million notes at 6.50% due July 2017	Aug. 31, 2013 $400 million notes at 6.50% due July 2017
Debt Instrument [Line Items]
Revolving credit facility current borrowing capacity				$ 64,000,000	$ 350,000,000	$ 50,000,000
Revolving credit facility, maturity date					Jun. 26, 2019
Revolving credit facility expired borrowing capacity					300,000,000
Revolving credit facility, maximum borrowing capacity					500,000,000
Stand by letters of credit outstanding amount						28,100,000
Minimum interest coverage ratio					250.00%
Maximum debt to capitalization ratio					60.00%
Minimum liquidity required					150,000,000
Actual interest coverage ratio					494.00%
Actual debt to capitalization ratio					48.00%
Debt instrument, issuance date					Jun. 26, 2014		May 20, 2013					Aug. 04, 2008		Jul. 17, 2007
Debt instrument, face amount							330,000,000				200,000,000	500,000,000	500,000,000	400,000,000	400,000,000
Debt instrument, interest rate, stated percentage							4.875%				5.625%	7.35%	7.35%	6.50%	6.50%
Debt instrument, maturity date							May 15, 2023					Aug. 15, 2018		Jul. 15, 2017
proceeds from debt, net of underwriting discounts and issuance costs								325,000,000
Debt extinguishment total cash outflow										205,300,000
Redemption purchase price to principal amount, percentage							100.00%		101.00%
Loss on debt extinguishment	0	4,758,000	0
Effective interest rate												6.40%		5.74%
Net proceeds from termination of interest rate swaps	0	0	52,733,000
Deferred gain of interest rate swaps	26,800,000	34,400,000
Amortization of interest rate swaps termination gain	7,597,000	12,470,000	5,815,000
Annual total borrowing				111,700,000
Annual total payments				111,700,000
Interest costs capitalized		1,000,000	1,300,000
Interest paid	$ 85,600,000	$ 82,500,000	$ 74,100,000