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Equity Financings and Warrants (Details Textual) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Jun. 28, 2019	Jan. 11, 2017
Equity Financing And Warrants [Line Items]
Common stock, par value	$ 0.001	$ 0.001
Common stock, shares issued	1,594,070	773,558
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	820,561	118,546
Net proceeds from issuance of common stock	$ 6.9	$ 3.4
Sales Agreement | JonesTrading
Equity Financing And Warrants [Line Items]
Common stock, par value				$ 0.001
Aggregate offering price of common stock authorized			$ 17.5	$ 7.3

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- Definition

Common stock, authorized offering amount under agreement to sell.

+ References

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- Definition

Equity financing and warrants.

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- Definition

The cash inflow associated with the amount received from entity's raising of capital via registered direct offering, net of related financing costs.

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- Definition

Selling commission per additional shares sold percentage.

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- Definition

Face amount or stated value per share of common stock.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(29))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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- Definition

Total number of common shares of an entity that have been sold or granted to shareholders (includes common shares that were issued, repurchased and remain in the treasury). These shares represent capital invested by the firm's shareholders and owners, and may be all or only a portion of the number of shares authorized. Shares issued include shares outstanding and shares held in the treasury.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(29))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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