Net Loss Per Share (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Net Loss Per Share Details
Net loss available for common shareholders - basic and diluted	$ (3,667)	$ (3,845)	$ (10,757)	$ (18,619)
Weighted-average shares outstanding - basic and diluted	28,448	24,974	26,739	20,406
Net loss per share - basic and diluted	$ (0.13)	$ (0.15)	$ (0.40)	$ (0.91)