Net Loss per Common Share (Net Loss Per Share Computation) (Details) (USD $) In Thousands, except Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Earnings Per Share [Abstract]
Net loss attributable to common stockholders	$ (23,321)	$ (18,087)	$ (16,213)
Weighted-average common shares outstanding (basic and diluted)	20,779,450	6,064,542	3,352,331
Basic and diluted net loss per share	$ (1.12)	$ (2.98)	$ (4.84)