OTHER LONG-TERM ASSETS (Details) $ in Thousands	9 Months Ended
	Jun. 30, 2017 USD ($) Security	Sep. 30, 2016 USD ($)	Jun. 30, 2015 USD ($)
Other long-term assets [Abstract]
Auction rate securities (ARS)	$ 5,319	$ 5,494
Other long-term assets	2,505	2,620
Long-term contract asset	2,350	2,900
Other long-term investments	1,153	1,028
Total	$ 11,327	12,042
Number of tax exempt municipal debt securities | Security	2
Minimum maturity period of municipal debt securities	10 years
Fair value of auction rate securities	$ 4,877
Gross unrecognized loss of ARS	442
Long-term contract asset face amount			$ 4,500
Long-term liability, SERP investments	$ 1,153
Accounting Standards Update 2015-03 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Debt issuance costs, noncurrent		$ (435)