SEGMENT INFORMATION - Schedule of Operating Income by Segment (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Schedule of Operating Income (Loss) by Segment
Income (loss) from operations	$ 40,105	$ 4,637	$ (7,139)	$ 2,195	$ 61,876	$ 53,023	$ (64,245)	$ 3,385	$ 39,798	$ 54,039	$ 29,435
Stock-based compensation									81,615	64,821	82,044
North America
Schedule of Operating Income (Loss) by Segment
Income (loss) from operations									65,728	19,909	(45)
Stock-based compensation									72,800	59,700	76,100
International
Schedule of Operating Income (Loss) by Segment
Income (loss) from operations									(25,930)	34,130	29,480
Stock-based compensation									$ 8,800	5,000	$ 5,700
Acquisition related (benefit) expense, net										700
IBM Lawsuit [Member]
Schedule of Operating Income (Loss) by Segment
Provision for loss contingency										$ 34,600