FAIR VALUE MEASUREMENTS - Changes to fair value measurement Level 3 (Details) - Liabilities - Level 3 - Fair Value, Recurring - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Derivative liability, beginning balance	$ 79,069	$ 17,974
Transfer to Level 3	6,640
Issuance of series warrants		4,600
Remeasurement to fair value	40,408	56,495
Derviative liability, ending balance	126,117	79,069
Series A Warrant Liabilities
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Derivative liability, beginning balance	0	0
Transfer to Level 3	6,640
Issuance of series warrants		0
Remeasurement to fair value	4,651	0
Derviative liability, ending balance	11,291	0
Series A Embedded Derivative Liabilities
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Derivative liability, beginning balance	26,728	17,974
Transfer to Level 3	0
Issuance of series warrants		0
Remeasurement to fair value	(8,280)	8,754
Derviative liability, ending balance	18,448	26,728
Series B Warrant Liabilities
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Derivative liability, beginning balance	52,341	0
Transfer to Level 3	0
Issuance of series warrants		4,600
Remeasurement to fair value	44,037	47,741
Derviative liability, ending balance	$ 96,378	$ 52,341