FAIR VALUE MEASUREMENTS AND FINANCIAL INSTRUMENTS - Changes in Level 3 Assets and Liabilities Measured at Fair Value on a Recurring Basis (Details) - Contingent Consideration Arrangements - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Contingent Consideration Arrangements
Balance at beginning of period	$ (1,965)	$ (21,821)	$ (2,647)	$ (33,871)
Fair value adjustments	(54)	(2,994)	(210)	(4,885)
Included in other comprehensive income (loss)	109	(14)	(1)	(1,073)
Settlements			948	15,000
Balance at end of period	$ (1,910)	$ (24,829)	$ (1,910)	$ (24,829)