FAIR VALUE OF FINANCIAL INSTRUMENTS (Details) - Recurring [Member] - USD ($) $ in Thousands	Dec. 31, 2018	Sep. 30, 2018
Assets [Abstract]
Cash and cash equivalents	$ 208,880	$ 352,921
Other long-term investments	1,242	1,137
Derivative financial instruments	643
Total assets	210,765	354,058
Liabilities [Abstract]
Derivative financial instruments	50	339
Total liabilities	50	339
Level 1 [Member]
Assets [Abstract]
Cash and cash equivalents	208,880	352,921
Other long-term investments	1,242	1,137
Derivative financial instruments	0
Total assets	210,122	354,058
Liabilities [Abstract]
Derivative financial instruments	0	0
Total liabilities	0	0
Level 2 [Member]
Assets [Abstract]
Cash and cash equivalents	0	0
Other long-term investments	0	0
Derivative financial instruments	643
Total assets	643	0
Liabilities [Abstract]
Derivative financial instruments	50	339
Total liabilities	50	339
Level 3 [Member]
Assets [Abstract]
Cash and cash equivalents	0	0
Other long-term investments	0	0
Derivative financial instruments	0
Total assets	0	0
Liabilities [Abstract]
Derivative financial instruments	0	0
Total liabilities	$ 0	$ 0

Fair value portion of probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.

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-Name Accounting Standards Codification
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-Section 50
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Fair value portion of currency on hand as well as demand deposits with banks or financial institutions. Includes other kinds of accounts that have the general characteristics of demand deposits. Also includes short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates.

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Fair value, after the effects of master netting arrangements, of a financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes assets not subject to a master netting arrangement and not elected to be offset.

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-Publisher FASB
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-Topic 210
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Fair value, after the effects of master netting arrangements, of a financial liability or contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes liabilities not subject to a master netting arrangement and not elected to be offset.

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Fair value of financial obligations, including, but not limited to, debt instruments, derivative liabilities, federal funds purchased and sold under agreements to repurchase, securities loaned or sold under agreements to repurchase, financial instruments sold not yet purchased, guarantees, line of credit, loans and notes payable, servicing liability, and trading liabilities.

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Amount of long-term investments classified as other.

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