CREDIT ARRANGEMENTS (Long-term Debt, Including the Deferred Gain from the Termination of the Interest Rate Swaps) (Details) - USD ($)	Feb. 28, 2018	Aug. 31, 2017	Jul. 31, 2017
Debt Instrument [Line Items]
Total debt	$ 825,858,000	$ 832,077,000
Less debt issuance costs	7,066,000	7,315,000
Total amounts outstanding	818,792,000	824,762,000
Less current maturities	18,958,000	19,182,000
Long-term debt	$ 799,834,000	805,580,000
2027 Notes
Debt Instrument [Line Items]
Weighted average interest rate	5.375%		5.375%
Total debt	$ 300,000,000	300,000,000
2023 Notes
Debt Instrument [Line Items]
Weighted average interest rate	4.875%
Total debt	$ 330,000,000	330,000,000
Other, including equipment notes
Debt Instrument [Line Items]
Total debt	49,608,000	52,077,000
Revolving credit facility
Debt Instrument [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity	$ 750,000,000
Revolving credit facility | 2022 Term Loan
Debt Instrument [Line Items]
Weighted average interest rate	2.909%
Line of Credit Facility, Maximum Borrowing Capacity	$ 146,250,000	$ 150,000,000