FAIR VALUE MEASUREMENTS (Reconciliation of Acquisition-Related Contractual Contingent Liabilities Using Significant Unobservable Inputs) (Details) - Level 3 - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Amount
Contingent consideration liabilities, beginning of period	$ 7,470	$ 10,495	$ 7,468
Payment of contingent consideration for previously acquired businesses	(50,000)	(9,619)	(1,104)
Effect of net foreign currency exchange rate changes	(387)	(525)	255
Contingent consideration liabilities, end of period	23,114	7,470	10,495
Interest and Other Income, net
Amount
Changes in fair value of contingent consideration included in Interest and other (loss)/income, net	8,782	1,827	1,776
Other 2019 Acquisitions
Amount
Acquisition			$ 2,100
Other 2020 Acquisitions
Amount
Acquisition		$ 5,292
PolSource
Amount
Acquisition	35,400
CORE
Amount
Acquisition	4,007
Emakina
Amount
Acquisition	213
Other 2021 Acquisitions
Amount
Acquisition	$ 17,629