EQUITY FINANCING - Additional Information (Detail) - USD ($)			3 Months Ended	9 Months Ended		12 Months Ended
	Jan. 07, 2021	Jan. 04, 2021	Mar. 31, 2021	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020	Dec. 31, 2019	Jan. 31, 2021	Jan. 31, 2019
Subsidiary Sale Of Stock [Line Items]
Aggregate proceeds from issuance of common stock				$ 57,385,000	$ 0
Common Stock
Subsidiary Sale Of Stock [Line Items]
Stock issued during period (in shares)			11,856,500
Underwriters | Common Stock
Subsidiary Sale Of Stock [Line Items]
Stock issued during period (in shares)		11,856,500
Sale of stock, price (in USD per share)		$ 4.85
Aggregate proceeds from issuance of common stock	$ 53,500,000
At The Market Offering Program
Subsidiary Sale Of Stock [Line Items]
Maximum common stock saleable shares, value								$ 42,900,000
At The Market Offering Program | Maximum
Subsidiary Sale Of Stock [Line Items]
Maximum aggregate offering price									$ 250,000,000
Maximum common stock saleable shares, value									$ 100,000,000
At The Market Offering Program | Common Stock
Subsidiary Sale Of Stock [Line Items]
Stock issued during period (in shares)				0		0	0