Stockholders' Equity (Details) $ / shares in Units, $ in Thousands										12 Months Ended
	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	Nov. 06, 2019 USD ($) $ / shares shares	Oct. 25, 2019 USD ($) $ / shares shares	Mar. 12, 2019 USD ($) $ / shares shares	Nov. 27, 2017 USD ($) $ / shares shares	Dec. 31, 2020 USD ($) $ / shares shares	Dec. 31, 2019 USD ($) shares	Apr. 02, 2020 $ / shares shares	May 30, 2019 $ / shares shares	Jul. 03, 2018 $ / shares
Class of Stock Disclosures [Abstract]
Warrants to purchase shares of common stock (in shares)					585,460	40,638	19,196
Warrants exercised to purchase common stock (in shares)										455,162
Proceeds from warrant exercises | $										$ 4,115	$ 0
Exercise price of warrants (in dollars per share) | $ / shares				$ 11.18	$ 16.50	$ 29.83	$ 42.30
Preferred stock, shares outstanding (in shares)										0	0
Issuance of common stock, net (in shares)					201,546	40,637	19,195
Public offering price (in dollars per share) | $ / shares						$ 33.60	$ 34.50
Gross proceeds from public stock offering | $					$ 9,700	$ 1,360	$ 660
Net proceeds from public stock offering | $					8,600
Down-round protection in connection with re-pricing of warrants | $					200
Beneficial conversion amount | $					$ 1,600
Warrant expiry period				5 years 6 months		5 years	5 years
Warrants exercisable period				6 months			6 months
Expected Stock Price Volatility [Member]
Class of Stock Disclosures [Abstract]
Warrants measurement input										1.3621
March 2019 Offering [Member]
Class of Stock Disclosures [Abstract]
Issuance of common stock, net (in shares)								15,173
Public offering price (in dollars per share) | $ / shares								$ 157.50
March 2020 Offering [Member]
Class of Stock Disclosures [Abstract]
Warrants to purchase shares of common stock (in shares)				138,715
Exercise price of warrants (in dollars per share) | $ / shares				$ 9.00
Issuance of common stock, net (in shares)				138,715
Public offering price (in dollars per share) | $ / shares				$ 9.00
Gross proceeds from public stock offering | $				$ 1,200
Net proceeds from public stock offering | $				$ 1,000
April 2020 Offering [Member]
Class of Stock Disclosures [Abstract]
Warrants to purchase shares of common stock (in shares)												85,506
Exercise price of warrants (in dollars per share) | $ / shares												$ 11.15
Issuance of common stock, net (in shares)			171,008
Public offering price (in dollars per share) | $ / shares												$ 13.02
Gross proceeds from public stock offering | $			$ 2,200
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)		59,966
Exercise price of warrants (in dollars per share) | $ / shares		$ 12.30
Issuance of common stock, net (in shares)		119,930
Public offering price (in dollars per share) | $ / shares		$ 14.18
Gross proceeds from public stock offering | $		$ 1,700
Warrant expiry period		5 years 6 months
August 2020 Offering [Member]
Class of Stock Disclosures [Abstract]
Issuance of common stock, net (in shares)	1,064,678
Public offering price (in dollars per share) | $ / shares	$ 13.50
Gross proceeds from public stock offering | $	$ 14,400
Net proceeds from public stock offering | $	$ 13,000
Number of shares issuable on the exercise of warrants (in shares)	1,064,678
Warrant expiry period										5 years
Warrants to Purchase Common Stock [Member]
Class of Stock Disclosures [Abstract]
Number of warrants vested (in shares)										0
Warrants to Purchase Common Stock [Member] | Minimum [Member]
Class of Stock Disclosures [Abstract]
Exercise price of warrants (in dollars per share) | $ / shares										$ 9.00
Warrants to Purchase Common Stock [Member] | Consultant [Member]
Class of Stock Disclosures [Abstract]
Warrants to purchase shares of common stock (in shares)													3,334
Exercise price of warrants (in dollars per share) | $ / shares										$ 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
Net proceeds from issuance of convertible preferred stock | $									$ 16,200
Conversion price (in dollars per share) | $ / shares				$ 9.00	$ 16.50	$ 29.83	$ 42.30	$ 157.50	$ 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)									18,000	127	535
Number of shares issuable on conversion of preferred stock (in shares)									9,557
Preferred stock, shares outstanding (in shares)										127	535
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
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)									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)									16
Exercise price of warrants (in dollars per share) | $ / shares									$ 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)									16
Exercise price of warrants (in dollars per share) | $ / shares									$ 1,890.00
Series G Convertible Preferred Stock [Member]
Class of Stock Disclosures [Abstract]
Gross proceeds from issuance of convertible preferred stock | $								$ 12,400
Net proceeds from issuance of convertible preferred stock | $								$ 11,000
Conversion price (in dollars per share) | $ / shares								$ 157.50
Number of consecutive trading days										30 days
Preferred stock, shares outstanding (in shares)											0
Beneficial conversion amount | $										$ 4,500
Beneficial ownership limitation								4.99%
Conversion of preferred stock into common stock (in shares)											63,685
Series G Convertible Preferred Stock [Member] | March 2019 Offering [Member]
Class of Stock Disclosures [Abstract]
Number of shares issuable on conversion of preferred stock (in shares)								1,910,536
Series G Convertible Preferred Stock [Member] | Warrant Series 1 [Member]
Class of Stock Disclosures [Abstract]
Exercise price of warrants (in dollars per share) | $ / shares								$ 157.50
Number of shares issuable on the exercise of warrants (in shares)								78,863
Series G Convertible Preferred Stock [Member] | Warrant Series 2 [Member]
Class of Stock Disclosures [Abstract]
Exercise price of warrants (in dollars per share) | $ / shares								$ 157.50
Number of shares issuable on the exercise of warrants (in shares)								78,863
Series H Preferred Stock [Member]
Class of Stock Disclosures [Abstract]
Conversion price (in dollars per share) | $ / shares					$ 16.50
Preferred stock, shares outstanding (in shares)										0
Issuance of common stock, net (in shares)					11,517,269
Public offering price (in dollars per share) | $ / shares					$ 16.50
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)										11,517,269