Warrants to Acquire Shares of Common Stock - Changes in Fair Value of Warrant Liability (Details) $ in Thousands	9 Months Ended
	Sep. 30, 2020 USD ($)
Class of Warrant or Right, Fair Value [Roll Forward]
Warrant liability, beginning balance	$ 52
Fair value of warrants granted	0
Fair value of warrants exercised	0
Adjustment to exercise price of warrants	0
Change in fair value of warrants	(25)
Warrant liability, ending balance	27
Series A Convertible Preferred
Class of Warrant or Right, Fair Value [Roll Forward]
Warrant liability, beginning balance	52
Fair value of warrants granted	0
Fair value of warrants exercised	0
Adjustment to exercise price of warrants	0
Change in fair value of warrants	(25)
Warrant liability, ending balance	27
Galena February 2017
Class of Warrant or Right, Fair Value [Roll Forward]
Warrant liability, beginning balance	0
Fair value of warrants granted	0
Fair value of warrants exercised	0
Adjustment to exercise price of warrants	0
Change in fair value of warrants	0
Warrant liability, ending balance	$ 0