SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - INTANGIBLES (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES
Goodwill	$ 16,300	$ 16,300	$ 10,168	$ 10,168