Summary of Significant Accounting Policies (Details 5) (USD $)	12 Months Ended				0 Months Ended	12 Months Ended					0 Months Ended	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2011 Term loans	Jan. 26, 2011 Initial term loan facility	Dec. 31, 2013 Initial term loan facility Warrants	Dec. 31, 2012 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. 30, 2011 Additional term loan after amendment	Dec. 31, 2013 Additional term loan after amendment Warrants	Dec. 31, 2012 Additional term loan after amendment Warrants	Oct. 05, 2012 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
Draw down under 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	12,644,000	251,000				119,000	114,000					153,000	138,000
Changes in fair value of warrants included in earnings	$ (13,354,000)	$ (710,000)	$ (85,000)			$ 5,000	$ 506,000					$ 15,000	$ 204,000