FAIR VALUE MEASUREMENTS - Summary of recurring level III assets (Details) - Level III - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Balance, beginning of period	$ 1,020	$ 1,081
Realized and unrealized gains (loss) included in earnings	563	(61)
Balance, end of period	$ 1,583	$ 1,020