Net Loss Per Share (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, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
BASIC AND DILUTED
Weighted average number of common shares outstanding													39,532	35,266	33,003
Net loss	$ (3,107)	$ (3,245)	$ (3,874)	$ (4,008)	$ (3,047)	$ (3,343)	$ (3,120)	$ (3,570)	$ (2,128)	$ (2,144)	$ (3,427)	$ (1,588)	$ (14,234)	$ (13,080)	$ (9,287)
Net loss per shares basic and diluted	$ (0.08)	$ (0.08)	$ (0.10)	$ (0.11)	$ (0.08)	$ (0.09)	$ (0.09)	$ (0.11)	$ (0.07)	$ (0.06)	$ (0.10)	$ (0.05)	$ (0.36)	$ (0.37)	$ (0.28)