Accrued Expenses and Other Current Liabilities (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Payables and Accruals [Abstract]
Commercial costs	$ 8,652	$ 4,038
Research costs	6,780	9,632
Payroll and employee benefits	12,967	9,338
Interest	1,195	0
Professional fees	4,722	3,494
Other current liabilities	95	95
Total accrued expenses and other current liabilities	$ 34,411	$ 26,597