SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Deposits (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Cash
Deposit with non-insured institutions	$ 33.3
Guyanese dollars
Cash
Cash (in GYD)	$ 12.6	$ 7.5
Minimum | Corporate bonds
Cash
Investment maturity term	3 months
Maximum | Corporate bonds
Cash
Investment maturity term	1 year