REVENUE RECOGNITION - Schedule of Customer Assets & Liabilities (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2020 USD ($)
Accounts receivable
Beginning balance	$ 168,502
Increase (decrease), net	1,286
Ending balance	169,788
Unbilled accounts receivable
Beginning balance	24,204
Increase (decrease), net	11,801
Ending balance	36,005
Deferred revenue (current)
Beginning balance	100,406
Increase (decrease), net	13,293
Ending balance	113,699
Deferred revenue (long-term)
Beginning balance	20,482
Increase (decrease), net	5,429
Ending balance	$ 25,911