FAIR VALUE OF FINANCIAL INSTRUMENTS (Details) - Recurring [Member] - USD ($) $ in Thousands	Jun. 30, 2016	Sep. 30, 2015
Assets [Abstract]
Cash and cash equivalents	$ 243,087	$ 354,190
Other long-term investments	979	1,720
Derivative financial instruments	423	14
Total assets	244,489	355,924
Liabilities [Abstract]
Derivative financial instruments	2,296	1,406
Total liabilities	2,296	1,406
Level 1 [Member]
Assets [Abstract]
Cash and cash equivalents	243,087	354,190
Other long-term investments	979	1,720
Derivative financial instruments	0	0
Total assets	244,066	355,910
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	423	14
Total assets	423	14
Liabilities [Abstract]
Derivative financial instruments	2,296	1,406
Total liabilities	2,296	1,406
Level 3 [Member]
Assets [Abstract]
Cash and cash equivalents	0	0
Other long-term investments	0	0
Derivative financial instruments	0	0
Total assets	0	0
Liabilities [Abstract]
Derivative financial instruments	0	0
Total liabilities	$ 0	$ 0