CASH AND CASH EQUIVALENTS (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Cash and Cash Equivalents [Line Items]
Total cash and cash equivalents	$ 27,285	$ 39,858	$ 112,162	$ 12,030
Cash at banks
Cash and Cash Equivalents [Line Items]
Total cash and cash equivalents	27,239	39,368
Cash held with brokers
Cash and Cash Equivalents [Line Items]
Total cash and cash equivalents	$ 46	$ 490