Consolidated Statements of Operations - USD ($)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Income Statement [Abstract]
Revenues	$ 0	$ 0	$ 0
Expenses:
Research and development	10,896,591	5,969,182	5,339,716
General and administrative	4,616,500	3,889,359	4,120,603
Total expenses	15,513,091	9,858,541	9,460,319
Loss before other income (expense) and taxes	15,513,091	9,858,541	9,460,319
Interest income	19,863	13,917	17,345
Interest expense	(133,905)	0	0
Financing expense	(88,939)	(62,683)	0
Change in fair value of warrant liability	2,925,258	529,774	642,411
Loss before taxes	(12,790,814)	(9,377,533)	(8,800,563)
Taxes	0	0	0
Net loss	$ (12,790,814)	$ (9,377,533)	$ (8,800,563)
Net loss per share (in usd per share)	$ (0.15)	$ (0.16)	$ (0.16)
Weighted average number of shares outstanding basic and diluted (in shares)	87,203,675	59,915,086	54,281,189