Consolidated Statements of Operations - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Operating expenses:
Research and development	$ 10,058	$ 10,273	$ 10,533
General and administrative	12,340	7,566	8,472
Total operating expenses	22,398	17,839	19,005
Operating loss	(22,398)	(17,839)	(19,005)
Other income (expense):
Interest income	60	5	15
Interest expense	(172)	(136)	(130)
Modification of warrants			(765)
Derivatives loss	(10,804)	(376)	(18,871)
Other expense, net	(10,916)	(507)	(19,751)
Net loss	$ (33,314)	$ (18,346)	$ (38,756)
Net loss per share, basic and diluted (in dollars per share)	$ (1.26)	$ (0.83)	$ (2.10)
Weighted average number of common shares outstanding, basic and diluted (in shares)	26,461,374	22,080,761	18,497,922