LEASES - Right-of-use lease assets and lease liabilities (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019
Right-of-use lease assets and lease liabilities
Operating lease right-of use-assets, net	$ 4,507	$ 4,739	$ 0
Current portion of operating lease liabilities	859	864	0
Long-term operating lease liabilities	3,896	4,044	0
Total operating lease liabilities	4,755	4,908
Finance right-of-use assets, net	4,668	4,641	0
Current portion of finance lease liabilities	4,602	4,616	18
Long-term finance lease liabilities	60	17	$ 18
Total finance lease liabilities	$ 4,662	$ 4,633