Net Loss Per Share (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		12 Months Ended
	Mar. 31, 2014	Mar. 31, 2013	Dec. 31, 2013
Net Loss Per Share Details
Net loss available for common shareholders - basic and diluted	$ (8,018)	$ (3,654)	$ (13,178)
Weighted-average shares outstanding - basic and diluted	34,842	25,240
Net loss per share - basic and diluted	$ (0.23)	$ (0.14)