FAIR VALUE MEASUREMENTS - Reconciliation of Level 3 Liabilities (Details) - USD ($) $ in Thousands	9 Months Ended
Sep. 30, 2021	Sep. 30, 2020
Contingent Forward Contract Liability
Level 3 Liabilities [Roll Forward]
Fair value-beginning of period	$ 0	$ 30,844
Issuance	2,167,332	793
Change in fair value	454,546	8,719
Settlement	(2,621,878)	(39,563)
Fair value-end of period	0	793
Convertible Preferred Stock Warrant Liability
Level 3 Liabilities [Roll Forward]
Fair value-beginning of period	2,960	1,755
Issuance	0	0
Change in fair value	6,976	171
Settlement	(9,936)	0
Fair value-end of period	0	$ 1,926
Common Stock Warrant Liability
Level 3 Liabilities [Roll Forward]
Fair value-beginning of period	0
Issuance	812,048
Change in fair value	24,787
Settlement	0
Fair value-end of period	$ 836,835

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 gain (loss) recognized in income from liability measured at fair value on recurring basis using unobservable input (level 3).

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)(1)
-URI http://asc.fasb.org/extlink&oid=123874694&loc=d3e19207-110258

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- Definition

Amount of issuances 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

Amount of 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

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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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-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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