RECEIVABLES, CONTRACT ASSETS, AND DEFERRED REVENUE - Summary of Contract Assets and Deferred Revenue (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2021	Dec. 31, 2020
Receivables [Abstract]
Contract assets	$ 14,031	$ 15,296
Long-term contract assets	10,097	7,777
Total contract assets	24,128	23,073
Deferred revenue	242,194	232,865
Long-term deferred revenue	6,041	8,991
Total deferred revenue	248,235	$ 241,856
Revenue recognized during the period that was included in deferred revenue	$ 172,100