Summary of Significant Accounting Policies (Schedule of Share-based Compensation Expense) (Details) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total share-based compensation expense	$ 1,362,716	$ 1,894,099	$ 2,565,961
Unrecognized share-based compensation expense related to unvested awards	1,300,000
Unrecognized share-based compensation expense related to unvested awards expected to be recognized in the period	1 year 9 months
Proceeds from stock options exercised	74,796	38,984	118,309
Research and Development [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total share-based compensation expense	333,735	518,375	754,554
General and Administrative Expense [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total share-based compensation expense	$ 1,028,981	$ 1,375,724	$ 1,811,407