Annual report pursuant to Section 13 and 15(d)

Capital Structure - Narrative (Details)

Capital Structure - Narrative (Details) $ / shares in Units, $ in Millions								1 Months Ended				3 Months Ended			12 Months Ended
	Sep. 17, 2021 USD ($) shares	Jun. 04, 2021 USD ($) $ / shares shares	Jun. 11, 2020 USD ($) shares	Mar. 17, 2020 USD ($) shares	Feb. 06, 2020 USD ($) shares	Feb. 03, 2020 shares	Dec. 26, 2018 shares	Aug. 31, 2021 USD ($) shares	Jul. 31, 2021 USD ($)	Apr. 30, 2021 shares	Jan. 31, 2021 USD ($) $ / shares shares	Dec. 31, 2021 class_of_stock $ / shares shares	Jun. 30, 2021 $ / shares shares	Mar. 31, 2020 shares	Dec. 31, 2021 USD ($) class_of_stock $ / shares shares	Dec. 31, 2020 $ / shares shares
Class of Stock [Line Items]
Number of classes of stock authorized to issue \| class_of_stock												2			2
Number of shares of capital stock authorized to issue (in shares)												205,000,000			205,000,000
Common stock, shares authorized (in shares)												200,000,000			200,000,000	200,000,000
Preferred stock, shares authorized (in shares)												5,000,000			5,000,000	5,000,000
Common stock, par value (in dollars per share) \| $ / shares												$ 0.001			$ 0.001	$ 0.001
Preferred stock, par value per share (in dollars per share) \| $ / shares												0.001			$ 0.001	$ 0.001
Net proceeds \| $															$ 72.0
Exercise price per share (in dollars per share) \| $ / shares											$ 0.001	$ 0.001			$ 0.001
Percent ownership threshold											9.99%
Proceeds from issuance of warrants \| $											$ 4.4
Preferred stock, shares outstanding (in shares)												0			0	1,257,143
Preferred Stock
Class of Stock [Line Items]
Conversion of preferred stock to common stock (in shares)															(1,257,143)	(1,600,000)
Common stock
Class of Stock [Line Items]
Exercise of pre-funded warrants (in shares)															308,697
Consideration issued (in shares)																3,893,361
Conversion of preferred stock to common stock (in shares)										6,285,715				8,000,000	6,285,715	8,000,000
Series B convertible preferred stock \| Preferred Stock
Class of Stock [Line Items]
Preferred stock conversion ratio							0.20								0.20
Shares converted (in shares)										1,257,143				1,600,000
Preferred stock, shares outstanding (in shares)												0			0
Aevi
Class of Stock [Line Items]
Consideration issued (in shares)						3,900,000
Horizon & Powerscourt Notes \| Notes Payable
Class of Stock [Line Items]
Proceeds from issuance of warrants \| $		$ 0.9
Warrant
Class of Stock [Line Items]
Number of shares issued (in shares)											1,676,923
Warrant \| Horizon & Powerscourt Notes \| Notes Payable
Class of Stock [Line Items]
Number of shares issued (in shares)		403,844											403,844
Exercise price per share (in dollars per share) \| $ / shares		$ 2.60											$ 2.60
Warrants or rights exercisable term		10 years											10 years
Nantahala Capital Management LLC
Class of Stock [Line Items]
Percentage of ownership	5.00%
Nantahala
Class of Stock [Line Items]
Number of shares available under warrant (in shares)											1,676,923	308,880			308,880
Exercise of pre-funded warrants (in shares)												308,697
Warrants outstanding (in shares)												1,368,043			1,368,043
Underwritten Public Offering
Class of Stock [Line Items]
Number of shares issued (in shares)	14,308,878		15,180,000								13,971,889
Net proceeds \| $	$ 29.0		$ 35.4								$ 37.7
Underwritten Public Offering \| Armistice
Class of Stock [Line Items]
Number of shares issued (in shares)	5,454,545		2,000,000								2,500,000
Underwritten Public Offering \| Nantahala
Class of Stock [Line Items]
Number of shares issued (in shares)											1,400,000
Sale of stock price per share (in dollars per share) \| $ / shares											$ 2.599
Underwritten Public Offering \| Officers
Class of Stock [Line Items]
Number of shares issued (in shares)			110,000
ATM Agreement
Class of Stock [Line Items]
Number of shares issued (in shares)								2,000,000
Net proceeds \| $								$ 5.2	$ 50.0
Armistice Purchase Agreement
Class of Stock [Line Items]
Number of shares issued (in shares)				1,951,219
Net proceeds \| $				$ 3.9
Registered Direct Offering
Class of Stock [Line Items]
Number of shares issued (in shares)					1,306,282
Net proceeds \| $					$ 5.1
Registered Direct Offering \| Armistice
Class of Stock [Line Items]
Number of shares issued (in shares)					1,256,282
Private Placement \| Series B convertible preferred stock \| Preferred Stock
Class of Stock [Line Items]
Preferred stock, shares authorized (in shares)							2,857,143