LEASES - Narrative (Details) - USD ($) $ in Thousands		1 Months Ended	3 Months Ended		12 Months Ended
	Mar. 15, 2021	Jun. 30, 2021	Mar. 31, 2021	Dec. 31, 2020	Dec. 31, 2021	Dec. 31, 2020	Mar. 26, 2021	Feb. 26, 2021	Oct. 31, 2020	Jul. 31, 2020
Lessee, Lease, Description [Line Items]
Operating lease right-of-use assets				$ 645	$ 0	$ 645
Property and equipment, net				189	12	189
Reed Road, Houston, TX
Lessee, Lease, Description [Line Items]
Amount paid upon closing of asset sale								$ 1,100
Lease exit agreement, cash receivable								900
Lease exit agreement, note receivable								$ 200
San Francisco Office Space
Lessee, Lease, Description [Line Items]
Operating lease right-of-use assets							$ 600
Lease liability							1,000
Lease termination fee	$ 900
Security deposits refund	$ 200	$ 200
Loss on termination of lease			$ 500		$ 500
Disposal Group, Held-for-sale, Not Discontinued Operations | R&D Facility
Lessee, Lease, Description [Line Items]
Operating lease right-of-use assets				500		500			$ 500
Lease liability				700		700			700
Property and equipment, net				2,300		2,300			$ 2,300
Accretion of lease liability				$ 1,300		$ 1,300
Lab equipment | San Francisco Office Space
Lessee, Lease, Description [Line Items]
Operating lease right-of-use assets							$ 100
Houston, Texas | Office space
Lessee, Lease, Description [Line Items]
Operating lease right-of-use assets										$ 500
Lease liability										$ 600