Unaudited Condensed Statements of Operations - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Income Statement [Abstract]
Revenue	$ 64	$ 64
Operating expenses:
Research and development, net	4,020	4,743
Selling, general and administrative	2,060	2,533
Total operating expenses	6,080	7,276
Loss from operations	(6,016)	(7,212)
Other (income) expense:
Amortization of debt discount	100	0
Interest income	(69)	(28)
Interest expense	345	0
Warrant liability fair value adjustment	(1,523)	0
Total other income	(1,147)	(28)
Net loss	(4,869)	(7,184)
Warrant liability fair value adjustment	(1,523)	0
Net loss attributable to common stockholders - diluted	$ (6,392)	$ (7,184)
Net loss per share attributable to common stockholders - basic
Net loss per share - basic (in dollars per share)	$ (0.19)	$ (0.52)
Net loss per share attributable to common stockholders - diluted
Net loss per share - diluted (in dollars per share)	$ (0.25)	$ (0.52)
Weighted average common shares outstanding:
Basic (shares)	25,364,429	13,905,613
Diluted (shares)	25,562,027	13,905,613