Annual report pursuant to Section 13 and 15(d)

Cover
- Document and Entity Information
Financial Statements
Notes to Financial Statements
Accounting Policies
- Summary of Significant Accounting Policies (Policies)
Notes Tables
Notes Details

Nature of Business (Details)

v3.19.3.a.u2

Nature of Business (Details) $ / shares in Units, $ in Thousands		1 Months Ended	12 Months Ended
	Apr. 09, 2019 USD ($) Agreement $ / shares shares	Nov. 30, 2019 USD ($) shares	Dec. 31, 2019 USD ($) $ / shares shares	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)
Stock Offering
Number of underwriting agreements \| Agreement	2
Gross proceeds from public offerings \| $	$ 70,000
Underwriting discounts and commissions and offering expenses \| $	$ 5,000
Net Loss \| $			$ 75,438	$ 62,279	$ 54,010
Accumulated deficit \| $			(292,983)	$ (217,545)
Cash equivalents and marketable securities \| $			$ 91,400
Class A Warrants
Stock Offering
Warrants to purchase common stock \| shares			2,118,344
Warrants, exercise price \| $ / shares			$ 8.625
Class A warrants maturity date			Oct. 10, 2022
Series A Convertible Preferred Stock
Stock Offering
Share price (in dollars per share) \| $ / shares			$ 6.57
Public Offering \| Class A Warrants
Stock Offering
Warrants, exercise price \| $ / shares	$ 8.625
Class A warrants maturity date	Oct. 10, 2022
Common Stock Agreement \| Public Offering \| Class A Warrants
Stock Offering
Warrants to purchase common stock \| shares	1,951,844
Share price (in dollars per share) \| $ / shares	$ 7.50		$ 7.50
Preferred Stock Agreement \| Public Offering \| Class A Warrants
Stock Offering
Warrants to purchase common stock \| shares	166,500
Share price (in dollars per share) \| $ / shares	$ 7,500
Preferred Stock Agreement \| Public Offering \| Series A Convertible Preferred Stock
Stock Offering
Shares issued \| shares	666
Common Stock \| At Market Sales Facility [Member]
Stock Offering
Shares issued \| shares		180,787
Aggregate gross proceeds \| $		$ 900
Common Stock \| Common Stock Agreement \| Public Offering
Stock Offering
Shares issued \| shares	8,667,333

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