Accrued Expenses and Other Current Liabilities (Details) (USD $)
In Thousands, unless otherwise specified
Dec. 31, 2014
Dec. 31, 2013
Accrued Expenses and Other Current Liabilities    
Research costs - Nordic $ 11,536 $ 17,998
Research costs - other 3,336 1,599
Payroll and employee benefits 1,659 1,005
Professional fees 1,304 426
Accrued interest on notes payable 234 852
Other 198 127
Total accrued expenses and other current liabilities $ 18,267 $ 22,007