RECEIVABLES, CONTRACT ASSETS, AND DEFERRED REVENUE- Contract Effective (Details) $ in Thousands	9 Months Ended
	Sep. 30, 2020 USD ($)
Receivables [Abstract]
2020	$ 105,380
2019	99,875
2018	39,281
2017	37,824
2016 and prior	34,919
Unbilled revenue total	$ 317,279
2020	33.00%
2019	32.00%
2018	12.00%
2017	12.00%
2016 and prior	11.00%
Total percentage of unbilled revenue	100.00%
Revenue recognized during the period that was included in deferred revenue	$ 170,500