SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Narrative (Details)	3 Months Ended
	Mar. 31, 2020 USD ($) segment shares	Mar. 31, 2019 USD ($)	Jan. 01, 2020 USD ($)	Dec. 31, 2019 USD ($) shares
Property, Plant and Equipment [Line Items]
Available-for-sale securities, cost basis				$ 2,000,000
U.S. treasury securities (included in short-term investments)				2,000,000
Unrealized loss				$ 0
Issuance of warrants (in shares) | shares	7,535,815			46,522
Impairment charges	$ 0	$ 0
Realized investment gains (losses)	0	0
Unrealized gain on investments	0	5,000
Income tax penalties and interest expense	$ 0	$ 0
Number of operating segments | segment	1
Operating lease liability	$ 306,000		$ 400,000
Operating lease right-of-use asset, net	$ 266,000		$ 400,000
Minimum
Property, Plant and Equipment [Line Items]
Estimated useful lives	3 years
Maximum
Property, Plant and Equipment [Line Items]
Estimated useful lives	5 years