INVESTMENT SECURITIES (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
Mar. 31, 2019	Dec. 31, 2018
Schedule of Held-to-maturity Securities [Line Items]
Amortized cost, as adjusted	$ 28,113	$ 26,951
Gross unrealized holding gains	15	2
Gross unrealized holding losses	3	10
Estimated fair value	28,125	26,943
Short-term Investments [Member] \| US Government Agencies Debt Securities [Member]
Schedule of Held-to-maturity Securities [Line Items]
Amortized cost, as adjusted	28,113	26,951
Gross unrealized holding gains	15	2
Gross unrealized holding losses	3	10
Estimated fair value	$ 28,125	$ 26,943

Amount of investment in debt security measured at amortized cost (held-to-maturity).

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
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-Section 45
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