FAIR VALUE MEASUREMENTS (Details) - USD ($) $ in Thousands	Jun. 30, 2017	Sep. 30, 2016
Assets:
Cash equivalents	$ 336	$ 435
Short-term investments	55,364
Restricted cash	25,301
Deferred compensation	6,238	5,773
Liabilities:
Deferred compensation	4,734	4,449
Quoted Prices in Active Markets for Identical Assets (Level 1)
Assets:
Cash equivalents	336	435
Short-term investments	55,364
Restricted cash	25,301
Deferred compensation	793	1,643
Liabilities:
Deferred compensation	0	0
Significant Other Observable Inputs (Level 2)
Assets:
Cash equivalents	0	0
Short-term investments	0
Restricted cash	0
Deferred compensation	5,445	4,130
Liabilities:
Deferred compensation	4,734	4,449
Significant Unobservable Inputs (Level 3)
Assets:
Cash equivalents	0	0
Short-term investments	0
Restricted cash	0
Deferred compensation	0	0
Liabilities:
Deferred compensation	$ 0	$ 0