Accounts Payable & Other Current Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Payables and Accruals [Abstract]
Accounts payable	$ 5,610	$ 1,629
Accrued expenses and other liabilities:
Employee benefits and compensation related accruals	4,111	3,085
General and administrative related accruals	2,908	2,389
Research and development related accruals	6,191	7,741
Accrued income taxes	0	1,721
Accounts payable and other current liabilities	$ 18,820	$ 16,565