RECEIVABLES, CONTRACT ASSETS, AND DEFERRED REVENUE - Summary of Contract Assets and Deferred Revenue (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Receivables [Abstract]
Contract assets	$ 6,195	$ 5,558
Long-term contract assets	5,664	5,420
Total contract assets	11,859	10,978
Deferred revenue	197,018	190,080
Long-term deferred revenue	5,630	5,407
Total deferred revenue	$ 202,648	$ 195,487