REVENUE - Changes in Contract Liability (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Revenue from Contract with Customer [Abstract]
Balance as of beginning of year	$ 603,687	$ 582,078
Recognized as revenue during period from beginning balance	(179,623)	(180,939)
Consideration deferred during period, net	203,308	203,136
Foreign currency translation adjustment and other	2,367	(588)
Balance as of end of year	$ 629,739	$ 603,687