Accounts Payable and Accrued Expenses - Accounts Payable and Accrued Expenses (Details) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Payables And Accruals [Abstract]
Trade payables	$ 1,023	$ 1,088
Employee compensation, benefits, and related accruals	440	762
Consulting and contracted research	1,209	506
Professional fees	167	214
Other	33	55
Total	$ 2,872	$ 2,625