Warrants to Acquire Shares of Common Stock - Warrants Outstanding (Details) shares in Thousands	9 Months Ended
	Sep. 30, 2020 shares
Class of Warrant or Right, Outstanding [Roll Forward]
Outstanding, beginning of period (in shares)	302
Granted (in shares)	4,012
Exercised (in shares)	(449)
Canceled/Expired (in shares)	(1)
Outstanding, end of period (in shares)	3,864
July 2020 PIPE Offering
Class of Warrant or Right, Outstanding [Roll Forward]
Outstanding, beginning of period (in shares)	0
Granted (in shares)	2,744
Exercised (in shares)	0
Canceled/Expired (in shares)	0
Outstanding, end of period (in shares)	2,744
January 2020 Offering
Class of Warrant or Right, Outstanding [Roll Forward]
Outstanding, beginning of period (in shares)	0
Granted (in shares)	819
Exercised (in shares)	0
Canceled/Expired (in shares)	0
Outstanding, end of period (in shares)	819
Pre-funded January 2020 Offering
Class of Warrant or Right, Outstanding [Roll Forward]
Outstanding, beginning of period (in shares)	0
Granted (in shares)	449
Exercised (in shares)	(449)
Canceled/Expired (in shares)	0
Outstanding, end of period (in shares)	0
June 2019 Offering
Class of Warrant or Right, Outstanding [Roll Forward]
Outstanding, beginning of period (in shares)	2
Granted (in shares)	0
Exercised (in shares)	0
Canceled/Expired (in shares)	0
Outstanding, end of period (in shares)	2
March 2019 Exercise Agreement
Class of Warrant or Right, Outstanding [Roll Forward]
Outstanding, beginning of period (in shares)	63
Granted (in shares)	0
Exercised (in shares)	0
Canceled/Expired (in shares)	0
Outstanding, end of period (in shares)	63
July 2018 Offering
Class of Warrant or Right, Outstanding [Roll Forward]
Outstanding, beginning of period (in shares)	208
Granted (in shares)	0
Exercised (in shares)	0
Canceled/Expired (in shares)	0
Outstanding, end of period (in shares)	208
Series A Convertible Preferred
Class of Warrant or Right, Outstanding [Roll Forward]
Outstanding, beginning of period (in shares)	19
Granted (in shares)	0
Exercised (in shares)	0
Canceled/Expired (in shares)	0
Outstanding, end of period (in shares)	19
2017 Equilibria
Class of Warrant or Right, Outstanding [Roll Forward]
Outstanding, beginning of period (in shares)	6
Granted (in shares)	0
Exercised (in shares)	0
Canceled/Expired (in shares)	0
Outstanding, end of period (in shares)	6
Galena February 2017
Class of Warrant or Right, Outstanding [Roll Forward]
Outstanding, beginning of period (in shares)	1
Granted (in shares)	0
Exercised (in shares)	0
Canceled/Expired (in shares)	0
Outstanding, end of period (in shares)	1
Galena Other
Class of Warrant or Right, Outstanding [Roll Forward]
Outstanding, beginning of period (in shares)	3
Granted (in shares)	0
Exercised (in shares)	0
Canceled/Expired (in shares)	(1)
Outstanding, end of period (in shares)	2