Summary of Significant Accounting Policies (Details 5) (USD $)	12 Months Ended			1 Months Ended	12 Months Ended					1 Months Ended	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2011 Term loans	Jan. 31, 2011 Initial term loan facility	Dec. 31, 2012 Initial term loan facility Warrants	Dec. 31, 2011 Initial term loan facility Warrants	Oct. 05, 2012 Initial term loan facility Warrants	Jan. 26, 2011 Initial term loan facility Warrants to purchase Series A Preferred Stock	May 01, 2012 Initial term loan facility Warrants to purchase common stock	Dec. 31, 2011 Additional term loan after amendment	Dec. 31, 2012 Additional term loan after amendment Warrants	Oct. 05, 2012 Additional term loan after amendment Warrants	Dec. 31, 2011 Additional term loan after amendment Warrants	Dec. 30, 2011 Additional term loan after amendment Warrants to purchase Series A Preferred Stock	May 01, 2012 Additional term loan after amendment Warrants to purchase common stock
Warrant liability
Maximum borrowing capacity			$ 30,000,000
Drawdown under the secured credit facility		30,000,000		15,000,000						15,000,000
Number of shares that can be purchased from warrants								375,000	93,750					200,000	49,999
Exercise price (in dollars per share)								$ 1.00	$ 4.00					$ 1.50	$ 5.00
Number of warrants exercised							75,000					26,667
Number of shares issued on exercise of warrants							49,137					15,172
Warrant liability at fair value	251,000	697,000			114,000	460,000					137,000		237,000
Changes in fair value of warrants included in earnings	$ (710,000)	$ (85,000)			$ 506,000	$ 85,000					$ 204,000