DESCRIPTION OF OPERATIONS AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Property and Equipment (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Property and Equipment
Property and equipment, net	$ 209	$ 368
Depreciation expense	$ 200	$ 100	$ 100
Capitalized Fees Paid to a Related Party
Capitalized fees paid to a related party, useful life	15 years
Equipment, furniture and fixtures | Minimum
Property and Equipment
Estimated useful life	5 years
Equipment, furniture and fixtures | Maximum
Property and Equipment
Estimated useful life	7 years
Software and computer equipment
Property and Equipment
Estimated useful life	3 years
Capitalized software
Property and Equipment
Estimated useful life	3 years