FAIR VALUE MEASUREMENTS Assets and Liabilities Measured on a Recurring Basis (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2015	Sep. 30, 2014
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	$ 146,116	$ 128,537
Short-term investments, Fair Value Disclosure	0	13,121
Derivative Liability, Fair Value, Gross Liability		92
Derivative Asset, Fair Value, Gross Liability	(123)
Held-to-maturity Securities, Fair Value	(550)	(550)
Total assets and liabilities at fair value	146,543	142,116
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	146,116	128,537
Short-term investments, Fair Value Disclosure	0	13,121
Derivative Liability, Fair Value, Gross Liability		0
Derivative Asset, Fair Value, Gross Liability	0
Held-to-maturity Securities, Fair Value	0	0
Total assets and liabilities at fair value	146,116	141,658
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	0	0
Short-term investments, Fair Value Disclosure	0	0
Derivative Liability, Fair Value, Gross Liability		92
Derivative Asset, Fair Value, Gross Liability	(123)
Held-to-maturity Securities, Fair Value	(550)	(550)
Total assets and liabilities at fair value	427	458
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	0	0
Short-term investments, Fair Value Disclosure	0	0
Derivative Liability, Fair Value, Gross Liability		0
Derivative Asset, Fair Value, Gross Liability	0
Held-to-maturity Securities, Fair Value	0	0
Total assets and liabilities at fair value	$ 0	$ 0