Summary of Significant Accounting Policies (Details 4)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Net loss per common share
Antidilutive securities excluded from computations of diluted net loss per common share	2,766,319	1,909,329	13,432,154
Convertible Preferred Stock [Member]
Net loss per common share
Antidilutive securities excluded from computations of diluted net loss per common share			12,329,330
Warrant [Member]
Net loss per common share
Antidilutive securities excluded from computations of diluted net loss per common share			72,029
Employee and Nonemployee Stock Options [Member]
Net loss per common share
Antidilutive securities excluded from computations of diluted net loss per common share	2,677,774	1,820,784	1,030,795
Warrants to Purchase Common Stock [Member]
Net loss per common share
Antidilutive securities excluded from computations of diluted net loss per common share	88,545	88,545