Consolidated Statements of Operations - USD ($)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Income Statement [Abstract]
Revenues	$ 0	$ 0	$ 0
Expenses:
Research and development	19,105,727	10,896,591	5,969,182
General and administrative	5,006,398	4,616,500	3,889,359
Total expenses	24,112,125	15,513,091	9,858,541
Loss before other income (expense) and taxes	(24,112,125)	(15,513,091)	(9,858,541)
Interest income	24,381	19,863	13,917
Interest expense	(1,311,836)	(133,905)	0
Financing expense	(498,520)	(88,939)	(62,683)
Change in fair value of warrant liability	3,812,398	2,925,258	529,774
Loss before taxes	(22,085,702)	(12,790,814)	(9,377,533)
Taxes	0	0	0
Net loss	$ (22,085,702)	$ (12,790,814)	$ (9,377,533)
Net loss per share (in usd per share)	$ (7.89)	$ (5.87)	$ (6.26)
Weighted average number of shares outstanding basic and diluted (in shares)	2,798,881	2,180,092	1,497,877