Summary of Unaudited Quarterly financial data (in thousands, except per share data) (Details) (USD $)	3 Months Ended
	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012
Summary of Unaudited Quarterly financial data
Product revenue	$ 5,658	$ 2,535	$ 5,581	$ 4,672	$ 4,558	$ 3,418	$ 6,244	$ 6,572
Research and development contract revenue	267	462	368	400	226	502	458	515
Net loss attributable to common shareholders	$ (28,929)	$ (15,948)	$ (9,338)	$ (8,576)	$ (8,474)	$ (10,325)	$ (6,480)	$ (6,583)
Basic and Diluted	$ (0.28)	$ (0.19)	$ (0.14)	$ (0.18)	$ (0.22)	$ (0.27)	$ (0.17)	$ (0.28)