Accounts Payable and Accrued Expenses - Accounts Payable and Accrued Expenses (Details) - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014
Payables And Accruals [Abstract]
Trade payables	$ 817	$ 553
Employee compensation, benefits, and related accruals	855	1,077
Consulting and contracted research	945	774
Professional fees	180	180
Other	26	80
Total	$ 2,823	$ 2,664