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Equity Financings and Warrants (Details Textual) - USD ($) $ / shares in Units, $ in Thousands		9 Months Ended		12 Months Ended
	Jun. 03, 2020	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020	Apr. 30, 2021	Jul. 22, 2020	Jul. 14, 2020	Jan. 11, 2017
Equity Financing And Warrants [Line Items]
Net proceeds from issuance of common stock		$ 24,070	$ 49,644
Common stock, par value		$ 0.001		$ 0.001
Common stock, shares issued		14,410,143		9,548,150
JonesTrading
Equity Financing And Warrants [Line Items]
Percentage of selling commission per additional shares sold								3.00%
Sales Agreement
Equity Financing And Warrants [Line Items]
Common stock, shares issued				2,214,301
Net proceeds from issuance of common stock				$ 14,400
Sales Agreement | JonesTrading
Equity Financing And Warrants [Line Items]
Common stock, par value								$ 0.001
Aggregate offering price of common stock authorized							$ 32,400	$ 7,300
2020 Sales Agreement
Equity Financing And Warrants [Line Items]
Net proceeds from issuance of common stock		$ 23,300		$ 28,900
Aggregate offering price of common stock authorized					$ 50,000	$ 54,000
Sale of common stock		4,861,993		5,066,279
Direct Offering
Equity Financing And Warrants [Line Items]
Common stock issued	348,000
Purchase price per share	$ 9.00
Pre-funded warrants to purchase shares of common stock	325,500
Purchase price per warrant	$ 8.999
Net proceeds from issuance of common stock	$ 5,300
Percentage of selling commission per additional shares sold	8.00%

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Number of securities into which the class of warrant or right may be converted. For example, but not limited to, 500,000 warrants may be converted into 1,000,000 shares.

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