REVENUE - Changes in Contract Liability (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020
Revenue from Contract with Customer [Abstract]
Balance as of beginning of period	$ 629,739	$ 603,687
Recognized as revenue during period from beginning balance	(109,558)	(103,089)
Consideration deferred during period, net	91,456	116,524
Foreign currency translation adjustment and other	1,499	(3,150)
Balance as of end of period	$ 613,136	$ 613,972