Stockholders' Equity - Equity Issuances (Details) - USD ($)		1 Months Ended				12 Months Ended	35 Months Ended
	Jul. 10, 2020	May 31, 2020	Apr. 30, 2020	Mar. 31, 2019	Aug. 31, 2018	Dec. 31, 2020	Dec. 31, 2020	Feb. 28, 2018
Lincoln Park Agreement
Class of Stock [Line Items]
Aggregate offering amount authorized per agreement				$ 26,000,000.0
Commitment shares issued as consideration per agreement (shares)				181,510
Number of shares sold (shares)				250,000
Price of shares sold (in dollars per share)				$ 4.00
Gross price for stock transaction				$ 1,000,000
Term of agreement (in months)				36 months
Number of shares allowable to direct for Regular Purchase (shares)				100,000
Maximum obligation per directed purchase transaction for Regular Purchase				$ 2,500,000
Maximum shares allowed in Accelerated Purchase as percent of shares in Regular Purchase (percent)				300.00%
Maximum shares allowed in Accelerated Purchase as percent of shares traded during specified period (percent)				30.00%
Maximum beneficial ownership allowable per agreement (percent)				9.99%
H.C. Wainwright Sales Amended Agreement
Class of Stock [Line Items]
Aggregate offering amount authorized per agreement				$ 17,600,000	$ 25,000,000.0			$ 25,000,000.0
Aggregate market value of common stock held by non-affiliates				$ 52,800,000
Maximum number of shares authorized per agreement (shares)				4,800,000
Commission on gross proceeds due to third party (percent)					3.00%
Stock issued (shares)						3,558,778	3,784,912
Proceeds from issuance of stock						$ 8,500,000	$ 9,500,000
April Purchase Agreement
Class of Stock [Line Items]
Number of shares sold (shares)			2,162,166
Price of shares sold (in dollars per share)			$ 2.3125
Number of shares called by warrants issued			1,081,083
Proceeds from issuance of stock			$ 5,000,000.0
Number of shares per each warrant			1
Warrant exercise price (in dollars per share)			$ 2.2500
Warrants expiration term			5 years 6 months
May Purchase Agreement
Class of Stock [Line Items]
Number of shares sold (shares)		2,084,850
Price of shares sold (in dollars per share)		$ 2.0625
Number of shares called by warrants issued		1,042,425
Proceeds from issuance of stock		$ 4,300,000
Number of shares per each warrant		1
Warrant exercise price (in dollars per share)		$ 2.0625
Warrants expiration term		5 years 6 months
July 2020 Private Placement
Class of Stock [Line Items]
Number of shares sold (shares)	969,694
Price of shares sold (in dollars per share)	$ 2.0625
Number of shares called by warrants issued	484,847
Proceeds from issuance of stock	$ 2,000,000.0
Number of shares per each warrant	1
Warrant exercise price (in dollars per share)	$ 2.0625
Warrants expiration term	5 years 6 months