Condensed Consolidated Statements of Operations and Comprehensive Loss (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Operating expenses:
Research and development	$ 4,246	$ 4,349
General and administrative	2,234	2,470
Total operating expenses	6,480	6,819
Loss from operations	(6,480)	(6,819)
Other income (expense):
Investment income	32	56
Other (expense) income, net	(50)	211
Total other (expense) income	(18)	267
Net loss	(6,498)	(6,552)
Unrealized gain on available-for-sale investments		23
Comprehensive loss	(6,498)	(6,529)
Net loss attributable to common stockholders	$ (6,498)	$ (6,552)
Net loss per share attributable to common stockholders - basic and diluted (in dollars per share)	$ (0.39)	$ (0.40)
Weighted-average common shares outstanding used in net loss per share attributable to common stockholders - basic and diluted (in shares)	16,636,201	16,507,586
Included in operating expenses, above, are the following amounts for non-cash stock based compensation expense:
Allocated share-based compensation	$ 845	$ 866
Included in other (expense) income, net, above, are the following amounts from forward foreign currency contracts:
Realized gains from forward foreign currency contracts		6
Unrealized gains from forward foreign currency contracts		178
Total		184
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	298	308
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	$ 547	$ 558