SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Adoption of the new revenue standard Balance Sheet (Details 7) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Accounts and unbilled receivables, net		$ 3,818
Prepaid expenses and other current assets	$ 284	216
Deferred tax assets	5,171	5,071
Accrued expenses	1,319	1,401
Stockholders' equity	$ 61,897	60,534	$ 59,004
Accounting Standards Update 2014-09 | As Reported
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Accounts and unbilled receivables, net		2,401
Prepaid expenses and other current assets		203
Deferred tax assets		5,402
Accrued expenses		1,184
Stockholders' equity		59,652
Accounting Standards Update 2014-09 | Adjustment
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Accounts and unbilled receivables, net		1,417
Prepaid expenses and other current assets		13
Deferred tax assets		(331)
Accrued expenses		217
Stockholders' equity		$ 882