STOCKHOLDERS' EQUITY - SALES AGREEMENTS (Details) - USD ($)			12 Months Ended
	Sep. 04, 2020	May 18, 2018	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
At Market Issuance Sales Agreements [Line Items]
Issuance of common stock in connection with at market offering, net of issuance costs			$ 20,385,000	$ 4,075,000	$ 19,295,000
2018 Sales Agreement
At Market Issuance Sales Agreements [Line Items]
Aggregate offering price of common stock		$ 100,000,000
Maximum commission rate (as a percent)		3.00%
Issuance of common stock in connection with at market offering, net of issuance costs (in shares)				3,496,616
Issuance of common stock in connection with at market offering, net of issuance costs				$ 4,075,000
2020 Sales Agreement
At Market Issuance Sales Agreements [Line Items]
Aggregate offering price of common stock	$ 100,000,000
Maximum commission rate (as a percent)	3.00%
Issuance of common stock in connection with at market offering, net of issuance costs (in shares)			10,571,556
Issuance of common stock in connection with at market offering, net of issuance costs			$ 20,385,000