Condensed Statements of Operations and Comprehensive Loss (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
OPERATING EXPENSES:
Research and development	$ 13,817	$ 15,543	$ 34,152	$ 49,070
General and administrative	2,836	1,621	8,045	4,643
Loss from operations	(16,653)	(17,164)	(42,197)	(53,713)
OTHER (EXPENSE) INCOME:
Other (expense) income, net		(2,607)	(506)	7,465
Loss on retirement of note payable			(203)
Interest income	35	11	42	27
Interest expense	(802)	(582)	(1,653)	(1,938)
NET LOSS	(17,420)	(20,342)	(44,517)	(48,159)
OTHER COMPREHENSIVE LOSS, NET OF TAX:
Unrealized gain from marketable securities	(11)	(3)	(10)
COMPREHENSIVE LOSS	(17,431)	(20,345)	(44,527)	(48,159)
(LOSS) EARNINGS ATTRIBUTABLE TO COMMON STOCKHOLDERS - BASIC AND DILUTED (Note 11)	$ (17,420)	$ (25,090)	$ (53,517)	$ (60,857)
LOSS PER SHARE:
Basic (in dollars per share)	$ (0.59)	$ (65.05)	$ (4.23)	$ (159.09)
Diluted (in dollars per share)	$ (0.59)	$ (65.05)	$ (4.23)	$ (159.09)
WEIGHTED AVERAGE SHARES:
Basic (in shares)	29,746,426	385,688	12,651,628	382,541
Diluted (in shares)	29,746,426	385,688	12,651,628	382,541