Condensed Consolidated Statements of Operations and Comprehensive Loss (Unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Research and Development Expense [Member]
Included in operating expenses, above, are the following amounts for non-cash stock based compensation expense:
Allocated share-based compensation	$ 168	$ 184	$ 797	$ 431
General and Administrative Expense [Member]
Included in operating expenses, above, are the following amounts for non-cash stock based compensation expense:
Allocated share-based compensation	519	427	1,702	1,063
Research and development	4,842	3,078	14,432	8,801
General and administrative	2,324	2,004	7,407	5,882
Total operating expenses	7,166	5,082	21,839	14,683
Loss from operations	(7,166)	(5,082)	(21,839)	(14,683)
Investment income	46	34	155	111
Other income (expense), net	13	(335)	120	(463)
Total other income (expense)	59	(301)	275	(352)
Net loss	(7,107)	(5,383)	(21,564)	(15,035)
Unrealized (loss) gain on available-for-sale investments	(2)	3	19	12
Comprehensive loss	(7,109)	(5,380)	(21,545)	(15,023)
Net loss attributable to common stockholders	$ (7,107)	$ (5,383)	$ (21,564)	$ (15,035)
Net loss per share attributable to common stockholders - basic and diluted (in dollars per share)	$ (0.43)	$ (0.33)	$ (1.30)	$ (0.91)
Weighted-average common shares outstanding used in net loss per share attributable to common stockholders - basic and diluted (in shares)	16,582,276	16,466,945	16,550,483	16,455,257
Allocated share-based compensation	$ 687	$ 611	$ 2,499	$ 1,494
Included in other (expense) income, net, above, are the following amounts from forward foreign currency contracts:
Realized losses from forward foreign currency contracts	(4)		(8)	(14)
Unrealized gains (losses) from forward foreign currency contracts	2	(314)	127	(426)
Total	$ (2)	$ (314)	$ 119	$ (440)