SUPPLEMENTAL CASH FLOW INFORMATION (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017	Mar. 31, 2017	Dec. 31, 2016
Supplemental Cash Flow Elements [Abstract]
Cash and cash equivalents	$ 40,894		$ 52,815
Restricted cash (cash held in escrow)	38,800		30,537
Restricted cash (certificate of deposits)	10,652
Restricted cash (held with Trustee)	5,948		2,975
Total cash and cash equivalents, and restricted cash	$ 96,294	$ 88,342	$ 86,327	$ 55,733