Condensed Consolidated Statements of Operations and Comprehensive Loss (Unaudited) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Revenues:
Total revenues	$ 436	$ 991	$ 650	$ 2,009
Operating expenses:
Research and development	1,794	1,669	3,190	3,492
Selling, general and administrative	2,949	2,943	5,570	5,995
Total operating expenses	5,014	4,728	9,067	9,709
Loss from operations	(4,578)	(3,737)	(8,417)	(7,700)
Interest expense	0	(365)	0	(704)
Other income, net	94	104	132	200
Initial loss on common stock warrant and common stock adjustment feature liability			(4,000)
Change in fair value of common stock warrant liabilities and common stock adjustment feature liability	(535)		(2,435)
Offering costs	(1,639)		(2,543)
Net loss before income taxes	(6,658)	(3,998)	(17,263)	(8,204)
Income tax provision	(11)	(8)	(21)	(18)
Net loss	$ (6,669)	$ (4,006)	$ (17,284)	$ (8,222)
Net loss per share attributable to common stockholders:
Basic and diluted	$ (2.02)	$ (1.88)	$ (6.29)	$ (3.77)
Weighted-average number of shares used in per share calculations:
Basic and diluted	3,307,667	2,133,241	2,746,931	2,178,647
Other comprehensive income, net of tax
Unrealized gains on available-for-sale securities		$ 7	$ 1	$ 6
Other comprehensive income		7	1	6
Comprehensive loss attributable to common stockholders	$ (6,669)	(3,999)	(17,283)	(8,216)
Product
Revenues:
Total revenues	188	195	249	400
Operating expenses:
Cost of product revenues	271	116	307	222
License
Revenues:
Total revenues	90	103	90	209
Contract Research And Government Grants
Revenues:
Total revenues	$ 158	$ 693	$ 311	$ 1,400