Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Revenues:
Revenues	$ 5,409	$ 7,579	$ 2,515
Operating expenses:
Research and development	20,652	25,179	23,703
General and administrative	10,781	9,138	8,205
Settlement costs (Note 13)	(667)	2,073
Operating Expenses, Total	30,766	36,390	31,908
Loss from operations	(25,357)	(28,811)	(29,393)
Other income (expense), net:
Interest expense, net	(2,191)	(2,373)	(1,949)
Change in fair value of PIPE Warrant liability	19,919	(33,740)	4,751
Other income (expense)	2,300		(195)
Other income (expense), net	20,028	(36,113)	2,607
Net loss before provision for income taxes	(5,329)	(64,924)	(26,786)
Provision for income taxes	0	(101)	(101)
Net loss	$ (5,329)	$ (65,025)	$ (26,887)
Basic net loss per share:
Net loss per share	$ (0.04)	$ (0.61)	$ (0.39)
Weighted average number of common shares outstanding	120,592	105,930	69,268
Diluted net loss per share:
Net loss per share	$ (0.19)	$ (0.61)	$ (0.39)
Weighted average number of common shares and dilutive common share equivalents outstanding	130,731	105,930	69,268
Collaboration and Licensing Revenue
Revenues:
Revenues	$ 4,947	$ 7,560	$ 2,515
Partnership Royalties
Revenues:
Revenues	$ 462	$ 19