Accounts Payable and Accrued Expenses - Accounts Payable and Accrued Expenses (Details) - USD ($) $ in Thousands	Sep. 30, 2016	Dec. 31, 2015
Payables And Accruals [Abstract]
Trade payables	$ 512	$ 1,088
Employee compensation, benefits, and related accruals	993	762
Consulting and contracted research	1,901	506
Professional fees	544	214
Other	26	55
Total	$ 3,976	$ 2,625