FAIR VALUE OF FINANCIAL INSTRUMENTS, Schedule of Fair Value of Financial Instruments (Details) - Fair Value, Measurements, Recurring [Member] - USD ($) $ in Thousands	Dec. 31, 2015	Sep. 30, 2015
Assets [Abstract]
Cash and cash equivalents	$ 218,118	$ 354,190
Other long-term investments	1,489	1,720
Derivative financial instruments	130	14
Total assets	219,737	355,924
Liabilities [Abstract]
Derivative financial instruments	653	1,406
Total liabilities	653	1,406
Level 1 [Member]
Assets [Abstract]
Cash and cash equivalents	218,118	354,190
Other long-term investments	1,489	1,720
Derivative financial instruments	0	0
Total assets	219,607	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	130	14
Total assets	130	14
Liabilities [Abstract]
Derivative financial instruments	653	1,406
Total liabilities	653	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