Accounts Payable and Accrued Expenses - Accounts Payable and Accrued Expenses (Details) - USD ($) $ in Thousands	Mar. 31, 2015	Dec. 31, 2014
Payables And Accruals [Abstract]
Trade payables	$ 632	$ 553
Employee compensation, benefits, and related accruals	384	1,077
Consulting and contracted research	288	774
Professional fees	171	180
Other	55	80
Total	$ 1,530	$ 2,664