Accrued Expenses - Components of Accrued Expenses (Details) - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014
Payables And Accruals [Abstract]
Professional fees	$ 5,785	$ 2,460
Accrued bonus	1,240	1,286
Accrued vacation	258	177
Accrued severance	29	179
Accrued payroll	582	213
Other	999	549
Total accrued expenses	$ 8,893	$ 4,864