Net Loss per Share of Common Stock (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Numerator:
Numerator for basic and diluted net loss per share attributable to common stockholders (in dollars)	$ (273)	$ (4,780)	$ (5,432)	$ (13,907)
Denominator:
Weighted average common shares outstanding for basic and diluted net loss per share	7,760,494	7,389,173	7,744,943	7,460,025
Basic and diluted (in dollars per share)	$ (0.04)	$ (0.65)	$ (0.70)	$ (1.86)
Securities excluded from the calculation of weighted average common shares outstanding
Anti-dilutive securities excluded in the computation of diluted earnings per share (in shares)	39,865,830	39,485,261	39,865,830	39,485,261
Preferred stock
Securities excluded from the calculation of weighted average common shares outstanding
Anti-dilutive securities excluded in the computation of diluted earnings per share (in shares)	32,563,192	32,563,192	32,563,192	32,563,192
Stock option awards
Securities excluded from the calculation of weighted average common shares outstanding
Anti-dilutive securities excluded in the computation of diluted earnings per share (in shares)	7,111,705	6,781,136	7,111,705	6,781,136
Restricted stock unit awards
Securities excluded from the calculation of weighted average common shares outstanding
Anti-dilutive securities excluded in the computation of diluted earnings per share (in shares)	50,000		50,000
Warrants to purchase preferred stock
Securities excluded from the calculation of weighted average common shares outstanding
Anti-dilutive securities excluded in the computation of diluted earnings per share (in shares)	140,933	140,933	140,933	140,933