WARRANTS - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Thousands	1 Months Ended		3 Months Ended					9 Months Ended		12 Months Ended
	Aug. 31, 2015	Jul. 31, 2015	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Sep. 30, 2020	Mar. 31, 2018	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2018	Jan. 31, 2017	Sep. 30, 2016
Common Stock Warrants [Line Items]
Placement warrants not exercised and remained outstanding (in shares)			2,036,733					2,036,733
Change in fair value of warrants			$ (876)			$ (2,020)		$ (5,577)	$ 1,281
Common Stock
Common Stock Warrants [Line Items]
Issuance of common stock from warrant exercises (in shares)				2,431	42,621
Issuance of common stock upon public offering, net (in shares)					11,856,500
March 2018 Direct Registered Offering | Common Stock
Common Stock Warrants [Line Items]
Issuance of common stock upon public offering, net (in shares)							4,090,000
March 2018 Direct Registered Offering | Series A Convertible Preferred Stock
Common Stock Warrants [Line Items]
Issuance of common stock upon public offering, net (in shares)							3,000,581
2015 Placement Warrants
Common Stock Warrants [Line Items]
Warrants issued (in shares)	198,760	198,760
Exercise price (in USD per share)	$ 5.00	$ 5.00
Common stock warrants, expiry term (in years)	5 years	5 years
Issuance of common stock from warrant exercises (in shares)										92,487
Number of warrant exercised (in shares)										159,010
Number of warrant expired (in shares)	39,750	39,750
Placement warrants not exercised and remained outstanding (in shares)			0					0
Common Stock Warrants | March 2018 Direct Registered Offering
Common Stock Warrants [Line Items]
Warrants issued (in shares)							1,418,116
Exercise price (in USD per share)							$ 8.31
Proceed from private placement and equity issuances, gross							$ 59,100
Fair value of warrants upon issuance							$ 7,400
Adjustments to additional paid in capital, warrant issued					$ 6,600
2016 Placement Warrants
Common Stock Warrants [Line Items]
Warrants issued (in shares)												1,720,512
Exercise price (in USD per share)			$ 2.95					$ 2.95
Placement warrants not exercised and remained outstanding (in shares)			536,711					536,711
2017 Placement Warrants
Common Stock Warrants [Line Items]
Warrants issued (in shares)											1,380,745
Exercise price (in USD per share)			$ 3.17					$ 3.17
Placement warrants not exercised and remained outstanding (in shares)			1,500,022					1,500,022