Stockholders' Equity (Details)												12 Months Ended
	Sep. 17, 2021 USD ($) $ / shares shares	Mar. 19, 2021 USD ($) $ / shares shares	Oct. 09, 2020	Oct. 06, 2020	Aug. 21, 2020 USD ($) $ / shares shares	May 05, 2020 USD ($) $ / shares shares	Apr. 01, 2020 USD ($) shares	Mar. 23, 2020 USD ($) $ / shares shares	Jan. 28, 2020 USD ($) $ / shares shares	Mar. 12, 2019 $ / shares	Nov. 27, 2017 USD ($) $ / shares shares	Dec. 31, 2021 USD ($) $ / shares shares	Dec. 31, 2020 USD ($) shares	Apr. 02, 2020 $ / shares shares	Nov. 06, 2019 $ / shares	Oct. 25, 2019 $ / shares	May 30, 2019 $ / shares shares	Jul. 03, 2018 $ / shares
Class of Stock Disclosures [Abstract]
Warrants exercised to purchase common stock (in shares) | shares													455,162
Proceeds from warrant exercises | $												$ 1,300	$ 4,115,000
Preferred stock, shares outstanding (in shares) | shares												0	0
Reverse stock split			0.03
Minimum [Member]
Class of Stock Disclosures [Abstract]
Reverse stock split				0.2
Maximum [Member]
Class of Stock Disclosures [Abstract]
Reverse stock split				0.03
Expected Stock Price Volatility [Member]
Class of Stock Disclosures [Abstract]
Warrants measurement input												1.3621
January 2020 Offering [Member]
Class of Stock Disclosures [Abstract]
Warrants to purchase shares of common stock (in shares) | shares									585,460
Exercise price of warrants (in dollars per share)								$ 9.00	$ 16.50
Issuance of common stock, net (in shares) | shares									201,546
Public offering price (in dollars per share)									$ 16.50
Gross proceeds from public stock offering | $									$ 9,700,000
Net proceeds from public stock offering | $									8,600,000
Down-round protection in connection with re-pricing of warrants | $									200,000
Beneficial conversion amount | $									$ 1,600,000
March 2020 Offering [Member]
Class of Stock Disclosures [Abstract]
Warrants to purchase shares of common stock (in shares) | shares								138,715
Exercise price of warrants (in dollars per share)								$ 11.18
Issuance of common stock, net (in shares) | shares								138,715
Public offering price (in dollars per share)								$ 9.00
Gross proceeds from public stock offering | $								$ 1,200,000
Net proceeds from public stock offering | $								$ 1,000,000.0
Warrant expiry period												5 years 6 months
Warrants exercisable period												6 months
April 2020 Offering [Member]
Class of Stock Disclosures [Abstract]
Warrants to purchase shares of common stock (in shares) | shares														85,506
Exercise price of warrants (in dollars per share)														$ 11.15
Issuance of common stock, net (in shares) | shares							171,008
Public offering price (in dollars per share)														$ 13.02
Gross proceeds from public stock offering | $							$ 2,200,000
Warrant expiry period												5 years 6 months
May 2020 Offering [Member]
Class of Stock Disclosures [Abstract]
Warrants to purchase shares of common stock (in shares) | shares						59,966
Exercise price of warrants (in dollars per share)						$ 12.30
Issuance of common stock, net (in shares) | shares						119,930
Public offering price (in dollars per share)						$ 14.18
Gross proceeds from public stock offering | $						$ 1,700,000
Warrant expiry period												5 years 6 months
August 2020 Offering [Member]
Class of Stock Disclosures [Abstract]
Issuance of common stock, net (in shares) | shares					1,064,678
Public offering price (in dollars per share)					$ 13.50
Gross proceeds from public stock offering | $					$ 14,400,000
Net proceeds from public stock offering | $					$ 13,000,000.0
Number of shares issuable on the exercise of warrants (in shares) | shares					1,064,678
Warrant expiry period												5 years
March 2021 Offering [Member]
Class of Stock Disclosures [Abstract]
Issuance of common stock, net (in shares) | shares		3,795,816
Gross proceeds from public stock offering | $		$ 20,900,000
Net proceeds from public stock offering | $		$ 18,900,000
September 2021 Offering [Member]
Class of Stock Disclosures [Abstract]
Issuance of common stock, net (in shares) | shares	4,005,588
Gross proceeds from public stock offering | $	$ 10,000,000.0
Net proceeds from public stock offering | $	$ 9,000,000.0
Warrants to Purchase Common Stock [Member]
Class of Stock Disclosures [Abstract]
Number of warrants vested (in shares) | shares												0
Warrants to Purchase Common Stock [Member] | Minimum [Member]
Class of Stock Disclosures [Abstract]
Exercise price of warrants (in dollars per share)												$ 2.50
Warrants to Purchase Common Stock [Member] | Maximum [Member]
Class of Stock Disclosures [Abstract]
Exercise price of warrants (in dollars per share)												41,916
Warrants to Purchase Common Stock [Member] | Consultant [Member]
Class of Stock Disclosures [Abstract]
Warrants to purchase shares of common stock (in shares) | shares																	3,334
Exercise price of warrants (in dollars per share)												$ 57.90					$ 95.40
Series F Convertible Preferred Stock [Member]
Class of Stock Disclosures [Abstract]
Gross proceeds from issuance of convertible preferred stock | $											$ 18,000,000.0
Net proceeds from issuance of convertible preferred stock | $											$ 16,200,000
Conversion price (in dollars per share)											$ 1,890.00							$ 890.40
Number of consecutive trading days considered for expiration												20 days
Number of consecutive trading days												30 days
Preferred stock issued (in shares) | shares											18,000	127	127
Number of shares issuable on conversion of preferred stock (in shares) | shares											9,557
Preferred stock, shares outstanding (in shares) | shares												127	127
Aggregate cash placement fee										8.00%
Series F Convertible Preferred Stock [Member] | Minimum [Member]
Class of Stock Disclosures [Abstract]
Percentage of volume weighted average price of common stock											300.00%
Trading volume for each trading day | $											$ 200,000
Series F Convertible Preferred Stock [Member] | March 2019 Offering [Member]
Class of Stock Disclosures [Abstract]
Conversion price (in dollars per share)										$ 157.50
Series F Convertible Preferred Stock [Member] | October 2019 Offering [Member]
Class of Stock Disclosures [Abstract]
Conversion price (in dollars per share)																$ 42.30
Series F Convertible Preferred Stock [Member] | November 2019 Offering [Member]
Class of Stock Disclosures [Abstract]
Conversion price (in dollars per share)															$ 29.83
Series F Convertible Preferred Stock [Member] | January 2020 Offering [Member]
Class of Stock Disclosures [Abstract]
Conversion price (in dollars per share)									$ 16.50
Exercise price of warrants (in dollars per share)									9.00
Series F Convertible Preferred Stock [Member] | March 2020 Offering [Member]
Class of Stock Disclosures [Abstract]
Conversion price (in dollars per share)								$ 9.00
Series F Convertible Preferred Stock [Member] | March 2021 Offering [Member]
Class of Stock Disclosures [Abstract]
Conversion price (in dollars per share)		$ 5.50
Exercise price of warrants (in dollars per share)		$ 5.50
Series F Convertible Preferred Stock [Member] | September 2021 Offering [Member]
Class of Stock Disclosures [Abstract]
Conversion price (in dollars per share)	$ 2.50
Exercise price of warrants (in dollars per share)	$ 2.50
Series F Convertible Preferred Stock [Member] | Warrants to Purchase Common Stock [Member]
Class of Stock Disclosures [Abstract]
Warrants to purchase shares of common stock (in shares) | shares											19,122
Series F Convertible Preferred Stock [Member] | Warrant Series 1 [Member]
Class of Stock Disclosures [Abstract]
Warrants to purchase shares of common stock (in shares) | shares											16
Exercise price of warrants (in dollars per share)											$ 1,890.00
Series F Convertible Preferred Stock [Member] | Warrant Series 2 [Member]
Class of Stock Disclosures [Abstract]
Warrants to purchase shares of common stock (in shares) | shares											16
Exercise price of warrants (in dollars per share)											$ 1,890.00
Series H Preferred Stock [Member]
Class of Stock Disclosures [Abstract]
Conversion price (in dollars per share)									$ 16.50
Preferred stock, shares outstanding (in shares) | shares													0
Maximum percentage of the applicable Unit offering price, by which exercise price can be lower than adjustment									10.00%
Conversion of preferred stock into common stock (in shares) | shares													11,517,269
Series H Preferred Stock [Member] | January 2020 Offering [Member]
Class of Stock Disclosures [Abstract]
Issuance of common stock, net (in shares) | shares									11,517,269