ACCOUNTS RECEIVABLE, NET (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Accounts receivable, net
Accounts receivable, gross	$ 48,390	$ 48,087
Less: Allowance for credit losses	(4,814)	(4,472)
Total	43,576	43,615
Billed
Accounts receivable, net
Accounts receivable, gross	36,388	35,921
Unbilled
Accounts receivable, net
Accounts receivable, gross	$ 12,002	$ 12,166