Accrued Expenses and Other Current Liabilities (Details) - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015
Payables and Accruals [Abstract]
Research costs - Nordic(1)	$ 2,675	$ 2,898
Research costs - other	5,530	5,178
Payroll and employee benefits	3,607	3,330
Professional fees	4,733	3,546
Total accrued expenses and other current liabilities	$ 16,545	$ 14,952