FAIR VALUE MEASUREMENTS - Changes to Fair Value Measurement Level 3 (Details) - Liabilities - Level 3 - Fair Value, Recurring - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2022	Mar. 31, 2021
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Derivative liability, beginning balance	$ 126,117	$ 79,069
Issuance of series warrants		6,640
Remeasurement to fair value	(28,098)	198,909
Derivative liability, ending balance	98,019	284,618
Series A Warrant Liabilities
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Derivative liability, beginning balance	11,291	0
Issuance of series warrants		6,640
Remeasurement to fair value	(896)	11,603
Derivative liability, ending balance	10,395	18,243
Series A Embedded Derivative Liabilities
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Derivative liability, beginning balance	18,448	26,728
Issuance of series warrants		0
Remeasurement to fair value	(3,942)	13,691
Derivative liability, ending balance	14,506	40,419
Series B Warrant Liabilities
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Derivative liability, beginning balance	96,378	52,341
Issuance of series warrants		0
Remeasurement to fair value	(23,260)	173,615
Derivative liability, ending balance	$ 73,118	$ 225,956

A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

No definition available.

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- Definition

Amount of increase (decrease) of financial instrument classified as a liability measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=123874694&loc=d3e19207-110258

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- Definition

Amount of purchases, (sales), issuances and (settlements) of financial instrument classified as a liability measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)(2)
-URI http://asc.fasb.org/extlink&oid=123874694&loc=d3e19207-110258

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- Definition

Fair value of financial instrument classified as a liability measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

+ References

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