Net Loss Per Common Share (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended			6 Months Ended	9 Months Ended		294 Months Ended
	Sep. 30, 2013	Jun. 30, 2013	Sep. 30, 2012	Jun. 30, 2013	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013
Numerator:
Net loss	$ (2,273)		$ (6,034)		$ (12,706)	$ (22,824)	$ (283,060)
Less: earnings attributable to convertible preferred stock	1,368		1,218		3,945	2,738
Numerator of basic and diluted EPS	$ (3,641)		$ (7,252)		$ (16,651)	$ (25,562)
Denominator:
Denominator for basic and diluted EPS: weighted-average common shares outstanding	60,847,000		43,336,000		50,517,000	40,331,000
Net loss per share attributable to common shareholders (basic and diluted) (in dollars per share)	$ (0.06)	$ (0.11)	$ (0.17)	$ (0.26)	$ (0.33)	$ (0.63)
Aggregate number of common equivalent shares (related to options, warrants and preferred stock) that have been excluded from computations of diluted net loss per common share					48,671,000	29,260,000