Consolidated Statements of Operations and Comprehensive Loss (unaudited) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Revenue	$ 2,948		$ 2,948
Operating expenses:
Research and development	1,773	971	4,558	2,974
General and administrative	1,041	943	2,697	2,360
Total operating expenses	2,814	1,914	7,255	5,334
Income (loss) from operations	134	(1,914)	(4,307)	(5,334)
Other income (expense):
Interest income (expense), net	10	(171)	(844)	(168)
Other expense	(5,325)	(18)	(5,424)	(13)
Other expense, net	(5,315)	(189)	(6,268)	(181)
Net loss	(5,181)	(2,103)	(10,575)	(5,515)
Unrealized gain (loss) on available-for-sale investments	12	(1)	(11)	(1)
Comprehensive loss	(5,169)	(2,104)	(10,586)	(5,516)
Net loss	(5,181)	(2,103)	(10,575)	(5,515)
Unrealized gain (loss) on available-for-sale investments	12	(1)	(11)	(1)
Accretion of redeemable convertible preferred stock to redemption value	(2,277)	(1,540)	(5,686)	(4,579)
Net loss attributable to common stockholders	$ (7,458)	$ (3,643)	$ (16,261)	$ (10,094)
Net loss per share attributable to common stockholders - basic and diluted (in Dollars per share)	$ (31.03)	$ (15.60)	$ (67.65)	$ (43.21)
Weighted-average number of common shares used in net loss per share attributable to common stockholders - basic and diluted (in Shares)	240,375	233,586	240,375	233,586