Quarterly Financial Information (unaudited) (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013
Quarterly Financial Information [Line Items]
Revenues	$ 45	$ 2	$ 23	$ 23	$ 22	$ 0	$ 0	$ 0	$ 93	$ 22
Cost of product revenues	23	1	12	12	11	0	0	0	48	11
Gross profit	22	1	11	11	11	0	0	0	45	11
Total Operating expenses	2,864	2,677	2,544	3,017	2,659	2,060	2,089	2,020	11,102	8,828
Operating loss	(2,842)	(2,676)	(2,533)	(3,006)	(2,648)	(2,060)	(2,089)	(2,020)	(11,057)	(8,817)
Other (expense) income, net	0	(4)	0	0	0	0	0	0	(4)	0
Loss before income taxes	(2,842)	(2,680)	(2,533)	(3,006)	(2,648)	(2,060)	(2,089)	(2,020)	(11,061)	(8,817)
Income taxes	0	0	0	0	0	0	0	0	0	0
Net loss	$ (2,842)	$ (2,680)	$ (2,533)	$ (3,006)	$ (2,648)	$ (2,060)	$ (2,089)	$ (2,020)	$ (11,061)	$ (8,817)
Basic and diluted net loss per share (in dollars per share)	$ (0.36)	$ (0.34)	$ (0.32)	$ (0.39)	$ (0.34)	$ (0.27)	$ (0.27)	$ (0.26)	$ (1.41)	$ (1.14)