INVESTMENT SECURITIES - Summary of investment securities (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018
Amortized cost, as adjusted	$ 27,798	$ 26,943
Gross unrealized holding gains	28	2
Gross unrealized holding losses	0	10
Estimated fair value	27,826	26,935
Short-term Investments [Member] \| US Government Agencies Debt Securities [Member]
Amortized cost, as adjusted	27,798	26,943
Gross unrealized holding gains	28	2
Gross unrealized holding losses	0	10
Estimated fair value	$ 27,826	$ 26,935

The amount of unrealized gain on debt securities classified as held to maturity.

No definition available.

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- Definition

The amount of unrealized loss on debt securities classified as held to maturity.

+ References

No definition available.

+ Details

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- Definition

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

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 45
-Paragraph 1
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=118954083&loc=d3e26610-111562

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 5
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=118939692&loc=d3e27232-111563

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- Definition

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

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 5
-Subparagraph (aa)
-URI http://asc.fasb.org/extlink&oid=118939692&loc=d3e27232-111563

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