Net Loss per Share (Details Textual)	Sep. 30, 2013	Dec. 31, 2012	Sep. 30, 2012	Dec. 31, 2011
Share-Based Compensation Arrangement By Share-Based Payment Award, Options, Outstanding, Number	3,804,580	4,453,746	4,258,746	2,979,010
Share-Based Compensation Arrangement By Share-Based Payment Award, Equity Instruments Other Than Options, Nonvested, Number	1,632,501	1,632,501	1,324,102	3,259,186