Condensed Consolidated Statements of Comprehensive Loss (Unaudited) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	May 31, 2012	Jun. 30, 2013	May 31, 2012
Condensed Consolidated Statements Of Comprehensive Loss (Unaudited) [Abstract]
Net product sales	$ 21	$ 0	$ 21	$ 0
Operating expenses:
Cost of sales	425	0	425	0
Research and development	6,215	6,020	14,627	9,991
Selling, general and administrative	9,379	4,105	17,242	6,557
Total operating expenses	16,019	10,125	32,294	16,548
Loss from operations	(15,998)	(10,125)	(32,273)	(16,548)
Interest income	16	91	171	198
Interest expense	(1,075)	(1)	(1,801)	(1)
Foreign currency transaction gain/ (loss)	(1)	45	(35)	63
Realized gain/ (loss) on short-term investments	(129)	0	(129)	0
Unrealized gain/ (loss) on short-term investments	107	56	0	176
Adjustment to fair value of common stock warrants	(7,041)	6,937	(5,981)	(877)
Net loss	(24,121)	(2,997)	(40,048)	(16,989)
Other comprehensive gain (loss):
Foreign currency translation adjustment	(1)	(11)	(89)	(9)
Comprehensive loss	$ (24,122)	$ (3,008)	$ (40,137)	$ (16,998)
Net loss per share:
Basic and diluted (in dollars per share)	$ (0.43)	$ (0.06)	$ (0.73)	$ (0.35)
Weighted-average shares outstanding used to compute:
Basic and diluted (in shares)	56,228	48,954	54,977	48,463