Accrued Expenses (Details) - USD ($)	Jun. 30, 2016	Dec. 31, 2015
Accrued Expenses
Accrued compensation	$ 636,093	$ 1,047,530
Accrued research and development	716,151	943,295
Other	164,804	282,166
Total accrued expenses	$ 1,517,048	$ 2,272,991