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CREDIT ARRANGEMENTS (Narrative) (Details)	3 Months Ended
	Nov. 30, 2017 USD ($)	Nov. 30, 2016 USD ($)	Nov. 30, 2017 PLN	Nov. 30, 2017 USD ($)	Aug. 31, 2017 PLN	Aug. 31, 2017 USD ($)	Jul. 31, 2017 USD ($)	May 31, 2013 USD ($)
Debt Instrument [Line Items]
Interest capitalized	$ 3,800,000	$ 1,600,000
Interest paid	9,400,000	8,400,000
CMCP
Debt Instrument [Line Items]
Revolving credit facility current borrowing capacity			PLN 225,000,000.0	$ 63,700,000.0	PLN 175,000,000.0	$ 49,100,000.0
Stand by letters of credit outstanding amount				1,600,000		1,300,000
Revolving credit facility, amount drawn				0		0
Total borrowing	0	0
Total payments	$ 0	$ 0
2027 Notes
Debt Instrument [Line Items]
Debt instrument, face amount				$ 300,000,000		300,000,000	$ 300,000,000
Weighted average interest rate			5.375%	5.375%			5.375%
2023 Notes
Debt Instrument [Line Items]
Debt instrument, face amount								$ 330,000,000
Weighted average interest rate			4.875%	4.875%
Debt instrument, interest rate, stated percentage								4.875%
Debt instrument, maturity date	May 15, 2023
Revolving credit facility
Debt Instrument [Line Items]
Revolving credit facility current borrowing capacity				$ 350,000,000
Revolving credit facility, maximum borrowing capacity				750,000,000
Revolving credit facility, amount drawn				$ 0		0
Minimum interest coverage ratio	2.50
Maximum debt to capitalization ratio	0.60
Actual interest coverage ratio			7.06	7.06
Actual debt to capitalization ratio			0.37	0.37
Revolving credit facility | Term Loan (Due 2022)
Debt Instrument [Line Items]
Revolving credit facility, maximum borrowing capacity				$ 150,000,000		150,000,000
Periodic payments, as percent of original principal amount	1.25%
Weighted average interest rate			2.83%	2.83%
Stand-by letters of credit
Debt Instrument [Line Items]
Revolving credit facility current borrowing capacity				$ 50,000,000
Stand by letters of credit outstanding amount				$ 3,300,000		$ 3,000,000

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