Net Loss Per Share (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Net Loss Per Share Details
Net loss available for common shareholders - basic and diluted	$ (3,436)	$ (4,971)	$ (7,090)	$ (14,774)
Weighted-average shares outstanding - basic and diluted	26,493	19,167	25,870	18,097
Net loss per share - basic and diluted	$ (0.13)	$ (0.26)	$ (0.27)	$ (0.82)