Stockholders' Equity - Warrants Narrative (Details) - $ / shares						12 Months Ended
	Oct. 30, 2019	Aug. 22, 2019	May 13, 2019	Apr. 05, 2019	Jun. 12, 2018	Dec. 31, 2019	Dec. 31, 2018
Class of Stock [Line Items]
Warrants granted (in shares)						7,437,454	3,450,000
Number of warrants exercised (in shares)						497,313	74,518
Underwriting Public Offering
Class of Stock [Line Items]
Warrants granted (in shares)					3,450,000
Exercise price of warrants (in dollars per share)					$ 6.60
Expiration period					5 years
Number of warrants exercised (in shares)						497,000
Pre-funded Warrant
Class of Stock [Line Items]
Warrants granted (in shares)						605,072
Exercise price of warrants (in dollars per share)						$ 0.01
Series B Warrant
Class of Stock [Line Items]
Vesting period				6 months
Series B Warrant | Registered Direct Offering
Class of Stock [Line Items]
Warrants granted (in shares)				382,166
Exercise price of warrants (in dollars per share)				$ 3.80
Expiration period				5 years 6 months
Series D Warrant
Class of Stock [Line Items]
Vesting period			6 months
Series D Warrant | Registered Direct Offering
Class of Stock [Line Items]
Warrants granted (in shares)			458,015
Exercise price of warrants (in dollars per share)			$ 3.15
Expiration period			5 years 6 months
Series F Warrant
Class of Stock [Line Items]
Vesting period		6 months
Series F Warrant | Registered Direct Offering
Class of Stock [Line Items]
Warrants granted (in shares)		727,802
Exercise price of warrants (in dollars per share)		$ 1.936
Expiration period		5 years 6 months
Series G Warrant | Registered Direct Offering
Class of Stock [Line Items]
Warrants granted (in shares)	2,756,340
Exercise price of warrants (in dollars per share)	$ 1.56
Expiration period	5 years 6 months
Series H Warrant | Registered Direct Offering
Class of Stock [Line Items]
Warrants granted (in shares)	2,756,340
Exercise price of warrants (in dollars per share)	$ 1.56
Expiration period	1 year 6 months
Placement Agent Warrant | Registered Direct Offering
Class of Stock [Line Items]
Warrants granted (in shares)	206,726
Exercise price of warrants (in dollars per share)	$ 2.2675
Expiration period	5 years 6 months