INTANGIBLE ASSETS AND GOODWILL - Schedule of Changes in Carrying Value of Goodwill (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Goodwill [Roll Forward]
Goodwill, gross, beginning of period	$ 392,302	$ 386,761
Accumulated impairment losses, beginning of period	(167,406)	(3,106)
Goodwill. beginning of period	224,896	383,655
Goodwill, gross, end of period	581,795	392,302
Accumulated impairment losses, end of period	(167,406)	(3,106)
Goodwill, end of period	414,389	389,196
ECI
Goodwill [Roll Forward]
Acquisition	189,493	0
Goodwill, end of period	189,493
Anova Data, Inc.
Goodwill [Roll Forward]
Acquisition	0	$ 5,541
Goodwill, end of period	$ 5,500