FAIR VALUE MEASUREMENTS - Acquisition-related Contingent Consideration (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Business Combination, Acquisition Related Contingent Consideration [Roll Forward]
Increase from revaluation of contingent consideration	$ 2,695	$ 0
Recurring basis
Business Combination, Acquisition Related Contingent Consideration [Roll Forward]
Beginning Balance	59,021
Ending Balance	60,299
Recurring basis | Level 3
Business Combination, Acquisition Related Contingent Consideration [Roll Forward]
Beginning Balance	59,021
Increase from revaluation of contingent consideration	2,695
Contractual payments accrued at March 31, 2016	(1,510)
Foreign currency impact	93
Ending Balance	$ 60,299