Percentage of commission paid to underwriters based on proceeds from offering.

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Amount of remaining available under its current sales agreement.

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Amount of currency on hand as well as demand deposits with banks or financial institutions. Includes other kinds of accounts that have the general characteristics of demand deposits. Also includes short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates. Excludes cash and cash equivalents within disposal group and discontinued operation.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Face amount or stated value per share of common stock.

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The cash inflow from the additional capital contribution to the entity.

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The cumulative amount of the reporting entity's undistributed earnings or deficit.

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Per share or per unit amount of equity securities issued.

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Equity impact of the value of new stock issued during the period. Includes shares issued in an initial public offering or a secondary public offering.

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Organization and Operations (Details) - USD ($) $ / shares in Units, $ in Thousands		3 Months Ended		9 Months Ended
	Jan. 30, 2020	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
Common Stock
Common stock, par value (in dollars per share)		$ 0.001		$ 0.001		$ 0.001
Accumulated deficit		$ (251,919)		$ (251,919)		$ (223,597)
Proceeds from public offering, net of issuance costs				(251,900)
Cash and cash equivalents		$ 52,856	$ 17,765	$ 52,856	$ 17,765	$ 9,899
Common stock
Common Stock
Common stock, par value (in dollars per share)		$ 0.001		$ 0.001
Number of shares issued		1,253,736	161,349	2,353,737	564,590
Gross proceeds from public offering		$ 1		$ 3	$ 1
Common stock \| Cowen
Common Stock
Percentage of commission paid to underwriter based on proceeds from common stock				3.00%
Common stock \| ATM
Common Stock
Number of shares issued				2,353,737
Share price (in dollars per share)		$ 7.13		$ 7.13
Gross proceeds from public offering				$ 16,800
Proceeds from public offering, net of issuance costs				16,300
Common stock \| First ATM Program \| Cowen
Common Stock
Remaining available under sales agreement		$ 27,900		$ 27,900
Common stock \| Over-Allotment option for underwriters \| Oppenheimer & Co. Inc
Common Stock
Number of shares issued	690,000
Common stock \| January 2020 Financing \| Oppenheimer & Co. Inc
Common Stock
Number of shares issued	5,290,000
Share price (in dollars per share)	$ 5.00
Gross proceeds from public offering	$ 26,500
Proceeds from public offering, net of issuance costs	$ 24,600