FAIR VALUE MEASUREMENTS (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Sep. 30, 2018
Assets:
Cash and cash equivalents	$ 66,376	$ 36,584
Short-term investments	5,991	13,170
Restricted cash	18,626	25,141
Other assets	6,621	6,817
Liabilities:
Deferred compensation	6,119	5,644
Quoted Prices in Active Markets for Identical Assets (Level 1)
Assets:
Cash and cash equivalents	66,376	36,584
Short-term investments	5,991	13,170
Restricted cash	18,626	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
Other assets	6,621	6,817
Liabilities:
Deferred compensation	6,119	5,644
Significant Unobservable Inputs (Level 3)
Assets:
Cash and cash equivalents	0	0
Short-term investments	0	0
Restricted cash	0
Other assets	0	0
Liabilities:
Deferred compensation	$ 0	$ 0