Unaudited Condensed Statements of Operations - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Income Statement [Abstract]
Revenue	$ 64	$ 64	$ 129	$ 129
Operating expenses:
Research and development, net	4,448	6,659	8,467	11,402
Selling, general and administrative	2,361	1,673	4,420	4,207
Total operating expenses	6,809	8,332	12,887	15,609
Loss from operations	(6,745)	(8,268)	(12,758)	(15,480)
Other (income) expense:
Amortization of debt discount	100	0	200	0
Interest income	(82)	(39)	(150)	(67)
Interest expense	360	0	709	0
Warrant liability fair value adjustment	(2,924)	(101)	(4,447)	(101)
Total other income	(2,546)	(140)	(3,688)	(168)
Net loss	$ (4,199)	$ (8,128)	$ (9,070)	$ (15,312)
Net loss per share - basic (USD per share)	$ (0.16)	$ (0.56)	$ (0.35)	$ (1.07)
Weighted average common shares outstanding - basic and diluted (shares)	25,813,675	14,590,733	25,590,293	14,248,166