ACCOUNTS RECEIVABLE, NET (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Accounts receivable, net
Accounts receivable, gross	$ 33,709	$ 48,087
Less: Allowance for credit losses	(5,653)	(4,472)
Total	28,056	43,615
Billed
Accounts receivable, net
Accounts receivable, gross	23,649	35,921
Unbilled
Accounts receivable, net
Accounts receivable, gross	$ 10,060	$ 12,166