RECEIVABLES, CONTRACT ASSETS, AND DEFERRED REVENUE RECEIVABLES, CONTRACT ASSETS, AND DEFERRED REVENUE - Summary of Contract Assets and Deferred Revenue (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Receivables [Abstract]
Contract assets	$ 5,558	$ 3,711
Long-term contract assets	5,420	2,543
Total contract assets	10,978	6,254
Deferred revenue	190,080	185,145
Long-term deferred revenue	5,407	5,344
Total deferred revenue	$ 195,487	$ 190,489