Accounts Payable and Accrued Expenses - Accounts Payable and Accrued Expenses (Details) - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015
Payables And Accruals [Abstract]
Trade payables	$ 655	$ 1,088
Employee compensation, benefits, and related accruals	763	762
Consulting and contracted research	1,218	506
Professional fees	246	214
Other	47	55
Total	$ 2,929	$ 2,625