FAIR VALUE MEASUREMENTS (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Sep. 30, 2018
Assets:
Cash and cash equivalents	$ 71,921	$ 36,584
Short-term investments	6,109	13,170
Restricted cash	16,664	25,141
Other assets	6,821	6,817
Liabilities:
Deferred compensation	6,284	5,644
Quoted Prices in Active Markets for Identical Assets (Level 1)
Assets:
Cash and cash equivalents	71,921	36,584
Short-term investments	6,109	13,170
Restricted cash	16,664	25,141
Other assets	0	0
Liabilities:
Deferred compensation	0	0
Significant Other Observable Inputs (Level 2)
Assets:
Cash and cash equivalents	0	0
Short-term investments	0	0
Restricted cash	0	0
Other assets	6,821	6,817
Liabilities:
Deferred compensation	6,284	5,644
Significant Unobservable Inputs (Level 3)
Assets:
Cash and cash equivalents	0	0
Short-term investments	0	0
Restricted cash	0	0
Other assets	0	0
Liabilities:
Deferred compensation	$ 0	$ 0