LEASES - Narrative (Details)	3 Months Ended		9 Months Ended
	Sep. 30, 2021 USD ($)	Sep. 30, 2020 USD ($)	Sep. 30, 2021 CAD ($) ft² term	Sep. 30, 2021 USD ($) ft² term	Sep. 30, 2020 USD ($)
Lessee, Lease, Description [Line Items]
Rent expense	$ 63,000	$ 64,000		$ 201,000	$ 195,000
Canada
Lessee, Lease, Description [Line Items]
Office space (in square feet) | ft²			31,100	31,100
Lease term	2 years		2 years	2 years
Renewal option | term			1	1
Renewal term	3 years		3 years	3 years
Monthly rent			$ 18,100	$ 14,300
Related operating expenses, per month			$ 18,200	14,300
Operating lease cost, including related operating cost	$ 79,000	$ 75,000		245,000	$ 223,000
Massachusetts
Lessee, Lease, Description [Line Items]
Monthly rent				2,100
Pennsylvania
Lessee, Lease, Description [Line Items]
Monthly rent				$ 18,000