COMPANY BACKGROUND - Amazon Agreement (Details) - Amazon Agreement $ / shares in Units, $ in Thousands		3 Months Ended
	Dec. 13, 2019 USD ($) item $ / shares shares	Mar. 31, 2022 shares	Mar. 31, 2021 shares
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Term of agreement	6 years
Number of extension option | item	2
Term of renewal of agreement	2 years
Threshold term of agreement	10 years
Warrants issued (in shares)	9,482,606
Exercise price (in dollars per share) | $ / shares	$ 15.17
Warrants vested (in shares)	632,183	189,652	189,652
Number of warrants that vest on achievement of each milestone (in shares)	63,217
Milestone achievement for warrants to vest | $	$ 8,000
Cumulative warrants vested (in shares)		1,833,311	1,074,704