Subsequent Event (Details) - USD ($)						1 Months Ended		12 Months Ended
	Mar. 14, 2022	Mar. 13, 2022	Jan. 07, 2022	Oct. 08, 2021	Feb. 21, 2020	Aug. 31, 2019	Mar. 31, 2019	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Jan. 06, 2022	Oct. 31, 2021	Feb. 28, 2021
Subsequent Event [Line Items]
Common stock that can be purchased with warrants (in shares)												13,333,324	450,000
Common Stock, Shares Authorized								150,000,000	150,000,000
2020 Shelf Registration Statement
Subsequent Event [Line Items]
Proceeds from issuance of common stock in public offering, net of offering costs	$ 4,300,000
Stock stated value	$ 1,000
Conversion price	$ 0.20
Preferred Stock, convertible, shares issuable	24,250,000
2020 Shelf Registration Statement | Series A Warrants
Subsequent Event [Line Items]
Common stock that can be purchased with warrants (in shares)	24,250,000
2020 Shelf Registration Statement | Series B Warrants
Subsequent Event [Line Items]
Common stock that can be purchased with warrants (in shares)	24,250,000
2020 Shelf Registration Statement | Series A Preferred Stock
Subsequent Event [Line Items]
Issuance of common stock (in shares)	2,425
2020 Shelf Registration Statement | Series B Preferred Stock
Subsequent Event [Line Items]
Issuance of common stock (in shares)	2,425
Private Placement | Common stock
Subsequent Event [Line Items]
Issuance of common stock (in shares)							8,426,750			8,426,750
Share price (in dollars per share)							$ 0.93
Proceeds from issuance of common stock in public offering, net of offering costs							$ 7,800,000
At-the-market sales | Common stock
Subsequent Event [Line Items]
Issuance of common stock (in shares)								6,915,151		12,242,436
At Market Sales on January 23
Subsequent Event [Line Items]
Proceeds from issuance of common stock in public offering, net of offering costs									$ 2,500,000
At Market Sales on January 23 | Common stock
Subsequent Event [Line Items]
Issuance of common stock (in shares)									1,801,528
At Market Sales on November 8
Subsequent Event [Line Items]
Proceeds from issuance of common stock in public offering, net of offering costs									$ 19,300,000
At Market Sales on November 8 | Common stock
Subsequent Event [Line Items]
Issuance of common stock (in shares)									10,440,908
At Market Sales on March 18 | Common stock
Subsequent Event [Line Items]
Issuance of common stock (in shares)								6,915,151
Proceeds from issuance of common stock in public offering, net of offering costs								$ 9,300,000
Public offering
Subsequent Event [Line Items]
Proceeds from issuance of common stock in public offering, net of offering costs								$ 21,081,000	$ 48,434,000	$ 12,687,000
Public offering | Common stock
Subsequent Event [Line Items]
Issuance of common stock (in shares)				26,666,648	17,250,000	14,526,315		26,666,648	17,250,000	14,526,315
Common stock that can be purchased with warrants (in shares)				13,333,324
Share price (in dollars per share)				$ 0.85	$ 3.00	$ 0.95
Common stock that can be purchased with one-half of warrant (in shares)				1
Proceeds from issuance of common stock in public offering, net of offering costs				$ 21,100,000	$ 48,400,000	$ 12,700,000
Subsequent event
Subsequent Event [Line Items]
Common Stock, Shares Authorized			300,000,000								150,000,000
Subsequent event | Perceptive Credit Agreement
Subsequent Event [Line Items]
Repayments of Debt			$ 5,000,000.0
Debt Instrument, Prepayment Premium Due			$ 0
Subsequent event | Series A Warrants | Securities Purchase Agreement
Subsequent Event [Line Items]
Common stock that can be purchased with warrants (in shares)		24,250,000
Warrants and rights outstanding, term		5 years
Stock stated value		$ 1,000
Conversion price		$ 0.20
Preferred Stock, convertible, shares issuable		24,250,000
Exercisable term		6 months
Exercise price of warrants (in dollars per share)		$ 0.26
Subsequent event | Series B Warrants | Securities Purchase Agreement
Subsequent Event [Line Items]
Warrants and rights outstanding, term		1 year 6 months
Proceeds from issuance of common stock in public offering, net of offering costs		$ 4,900,000
Exercisable term		6 months
Exercise price of warrants (in dollars per share)		$ 0.26
Subsequent event | Series A Preferred Stock | Securities Purchase Agreement
Subsequent Event [Line Items]
Issuance of common stock (in shares)		2,425
Subsequent event | Series B Preferred Stock | Securities Purchase Agreement
Subsequent Event [Line Items]
Issuance of common stock (in shares)		2,425