FAIR VALUE MEASUREMENTS - SCHEDULE OF SHORT-TERM INVESTMENTS (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	$ 9,016	$ 13,936
Gross Unrealized Holding Gains	10	0
Gross Unrealized Holding Losses	0	(6)
Fair Value	9,026	13,930
U.S. Treasury securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	9,016	13,936
Gross Unrealized Holding Gains	10	0
Gross Unrealized Holding Losses	0	(6)
Fair Value	$ 9,026	$ 13,930

Amount, before tax, of unrealized gain in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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Amount, before tax, of unrealized loss in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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Amortized cost of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
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-SubTopic 10
-Section 50
-Paragraph 2
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-Publisher FASB
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Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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