RECEIVABLES, CONTRACT ASSETS, AND DEFERRED REVENUE - Summary of Contract Assets and Deferred Revenue (Details) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Receivables [Abstract]
Contract assets	$ 5,323	$ 5,558
Long-term contract assets	4,903	5,420
Total contract assets	10,226	10,978
Deferred revenue	195,996	190,080
Long-term deferred revenue	6,587	5,407
Total deferred revenue	$ 202,583	$ 195,487