CREDIT ARRANGEMENTS (Narrative) (Details)	3 Months Ended		9 Months Ended
	May 31, 2018 USD ($)	May 31, 2017 USD ($)	May 31, 2018 USD ($)	May 31, 2017 USD ($)	May 31, 2018 PLN (zł)	May 31, 2018 USD ($)	Feb. 21, 2018 USD ($)	Aug. 31, 2017 PLN (zł)	Aug. 31, 2017 USD ($)	Jul. 31, 2017 USD ($)	May 31, 2013 USD ($)
Debt Instrument [Line Items]
Document Period End Date			May 31, 2018
Interest capitalized	$ 500,000	$ 2,900,000	$ 7,300,000	$ 6,600,000
Interest paid			$ 30,200,000	$ 41,400,000
CMCP
Debt Instrument [Line Items]
Revolving credit facility current borrowing capacity					zł 225,000,000.000000	$ 60,950,833.000000		zł 175,000,000	$ 49,099,377.1393000000
Stand by letters of credit outstanding amount						$ 1,700,000			1,300,000
2027 Notes
Debt Instrument [Line Items]
Debt instrument, face amount										$ 300,000,000
Weighted average interest rate					5.375%	5.375%				5.375%
2026 Notes
Debt Instrument [Line Items]
Debt instrument, face amount						$ 350,000,000
Weighted average interest rate					5.75%	5.75%
Debt issuance costs						$ 5,300,000
2023 Notes
Debt Instrument [Line Items]
Debt instrument, face amount											$ 330,000,000
Weighted average interest rate					4.875%	4.875%					4.875%
Revolving credit facility
Debt Instrument [Line Items]
Revolving credit facility current borrowing capacity						$ 350,000,000
Minimum liquidity required						150,000,000
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					7.89	7.89
Actual debt to capitalization ratio					0.45	0.45
Revolving credit facility | 2022 Term Loan
Debt Instrument [Line Items]
Weighted average interest rate					3.103%	3.103%
Periodic payments, as percent of original principal amount (percent)			1.25%
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
2018 Term Loan | Revolving credit facility
Debt Instrument [Line Items]
Periodic payments, as percent of original principal amount (percent)			1.25%
Revolving credit facility, maximum borrowing capacity							$ 200,000,000