FAIR VALUE MEASUREMENTS OF CERTAIN LIABILITIES - Narrative (Details) - USD ($) $ / shares in Units, $ in Thousands	Jun. 30, 2021	Dec. 31, 2020	Jan. 15, 2019	Feb. 21, 2018
Class of Warrant or Right [Line Items]
Warrant liability	$ 2,013	$ 1,725
CBG Acquisition Warrants
Class of Warrant or Right [Line Items]
Warrants outstanding (in shares)	40,000	40,000
Exercise price of warrants (in usd per share)	$ 10.00	$ 10.00	$ 6.00	$ 10.00
Warrants obligated to issue (in shares)	5,710,000	5,710,000	5,710,000	5,710,000

Exercise price per share or per unit of warrants or rights outstanding.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=123467817&loc=d3e21475-112644

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Number of securities into which the class of warrant or right may be converted. For example, but not limited to, 500,000 warrants may be converted into 1,000,000 shares.

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Number of warrants or rights outstanding.

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Fair value, after the effects of master netting arrangements, of a financial liability or contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset, expected to be settled after one year or the normal operating cycle, if longer. Includes assets not subject to a master netting arrangement and not elected to be offset.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 20
-Section 50
-Paragraph 3
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=51824906&loc=SL20225862-175312

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