Accrued Expenses and Other Current Liabilities (Details) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2014	Dec. 31, 2013
Accrued Expenses and Other Current Liabilities
Research costs - Nordic	$ 13,950	$ 17,998
Research costs - other	5,413	1,599
Payroll and employee benefits	888	1,005
Professional fees	1,296	426
Vacation	151	69
Interest on notes payable	127	852
Other	86	58
Total accrued expenses and other current liabilities	$ 21,911	$ 22,007